He post also said the XSX was good but he thought the PS5 was better .
First post of the devs react to PS5 thread.
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NX Gamer: PS5 Full Spec Analysis | A new generation is Born
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He post also said the XSX was good but he thought the PS5 was better .
First post of the devs react to PS5 thread.
Another factor to consider are the actual game engines themselves.
UE4, for example, currently lacks the ability to access and use select mesh asset data on initialization (say only the most relevant LODs). Instead the engine gathers and stores all associated memory with that asset into RAM. Not a bad engine architecture for slow mechanical drives, but it doesn't play to the strengths of SSDs with no needle to contend with.
Similarly with animations, UE4 is not built around prioritizing anims to load from disc. Pawn anim graphs will load all referenced animations together. Typically a character won't load until that step is complete, unless you are Respawn and make the call to allow enemies to charge at you in a T-pose while the block of animation on disc is being acessed.
In other words, while the PS5 hardware may be capable of a fundomental shift like Cerny has talked about, not every engine will be ready to work that way.
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Well, no actually. Per that developer 'the faster the better' wrt IO speed.
See the last paragraph of my last post, though. It may not be that way for all games. Indeed some may top out on their optimal IO needs well within the XSX's budget. But I don't see how anyone could make a general statement to that effect at this point, or to dismiss the possibility that that won't be the case. I think it's fairly reasonable speculation that there could be games next-gen with IO/asset demands that gel better to a faster drive than even XSX has, even if that 'only' means, for example, reduced temporal artifacts wrt asset quality.
We'll see what kind of games SIE WWS will make as well as third parties who have exclusive PS5 games.
As for multi-platform games, they'll be hindered by the lowest common denominator (last-gen is cross-gen, or Lockhart), so we shouldn't expect anything there except resolution/framerate differences.
As for multi-platform games, they'll be hindered by the lowest common denominator (last-gen is cross-gen, or Lockhart), so we shouldn't expect anything there except resolution/framerate differences.
There's no denying that a switch to SSD as a baseline may change the way some games are built. There's one difference though:
There's a narrative that 5.5GB/s is some magic numbers as a baseline and that anything under it means it'll have to be downscaled heavily in term of game design, as if it was some minimum to achieve things or as if everyone is going to max out such numbers.
Of course not, but it might be a visually perceptible difference to the LoD behaviour if one can gets closer to optimal lod behaviour than the other. Hence, an effect on visuals.
I completely agree with that. We don't know what benefits Cerny's vision will have over MS's. We only have seen some devs say they're happy Sony went the way they did.
My current thought is that I wish Sony had went the way of MS in architecture and priorities, but I'm open to my opinion changing when we see the games.
https://twitter.com/_ArtIsAVerb/status/1240390141232939012 is that not a good eg of that .
We also have a dev say this.
What John is saying sounds pretty right to me! I don't want to down play GPU power, but I promise everybody that you will be absolutely blown away by visuals on both consoles. However, the SSDs are the big difference when coming into this gen. We're not talking about "load times" in the classic sense. That's an antiquated way of thinking about data coming from your hard drive. For the last 10+ years we've been streaming worlds on the fly. The problem is that our assets are absolutely huge now, as are our draw distances, and our hard drives can't keep up. It means that as you move through the world we're trying to detect and even predict what assets need loading. Tons of constraints get put into place due to this streaming speed.
An ultra fast drive like the one in PS5 means you could be load in the highest level LOD asset for your models way further than you could before and make worlds any way you want without worry of it streaming in fast enough. The PS5 drive is so fast I imagine you could load up entire neighborhoods in a city with all of their maps at super high resolution in a blink of an eye. It's exciting. People don't realize that this will also affect visuals in a big way. If we can stream in bigger worlds and stream in the highest detail texture maps available, it will just look so much better.
I think the Xbox drive is also good! The PS5 drive is just "dream level" architecture though.
Of course XSX will be able to do all of this and we have to see how the PS5 drive being 2 times faster will effect things.
This!
Era is so rich with so much expert knowledge. Devs from Moon, 343, Dice, DF etc. Would be a pity if they all left due to the hostility and baseless accusations.
Yeah I indeed mention that right in that post I think. The speed of LOD changes in my response to him.
At high Camera speed, presuming that the i/o is the limiting factor for something and not geometry throughput of the GPU (as assets do not have draw distance and LOD Ranges due to i/ only, but usually questions of shading and overdraw are very important), then PS5 would have the advatange of less temporal lag on their draw in or perhaps the perceptual Range and which an object dissolves in
Of course XSX could do that too. But unlike in the conjectured PS5 case, there would be a noticeable lag between the user hitting the Guide button, and actually being in the OS. So possible, but with no QOL improvement as proposed for Sony.
This is incorrect. The 2.5GB/s and 5.5GB/s raw numbers don't account for differing compression approaches. But both platform holders have also given real-world average metrics including compression: 8-9GB/s for PS5, and 4.8GB/s for XSX. Note that the ratio is smaller here; that's presumably the effect of Microsoft's other implementations. But the performance is still at least 67% higher on PS5, up to 95%.
That's not even a Beyond3D Post...it is a link to a post from the old site. Which is banned here for many obvious reasons.
You don't know that. You don't know what BCPack could possibly do.
How about we wait and see? The fact remains though... better compression means better utilization of RAM size, AND bandwidth.
The last few days have been truly embarrassing for our community.
You love that number don't you? The X is far superior when it comes to Ray Tracing by a significant percentage and I am not even going to start praising it. Numbers on paper is one thing, the execution is another.
I gave you two examples in my post.
Why do you presume that teleportation has to happen in one frame?
So you are saying XSX games will look worse than PS5 games, if developers try to implement a certain movement speed for their game? That was exactly one of the points I was trying to make. The SSD will not just improve loading times.
Nobody claimed that the difference is comparable to the difference between an NVMe SSD and a 5400 RPM drive. I'm not sure why this talking point has spread so much in the last few days, plenty of people claiming that "people think there are 5400 RPM drives in the XSX". Nobody thinks that.
And of course you can find ways to mitigate the lower SSD speed of the XSX. But like you said above, then you have to lower details. I was talking about things that are not possible if you want to have the exact same visuals.
Not sure why you are talking about the quality of geometry, you probably could have just better textures and stuff like that.
Really don'y see how the X is far superior when it comes to Ray Tracing .
Better yes but not far superior with 15% give or take.
Where is that narrative? Do you know what I see? Strawmen. Everywhere. Nobody claims that exactly 5.5 GB/s can suddenly do "magic". This is a narrative that you are creating. People are simply saying that the SSD is 129% faster than the XSX SSD, and that it means there will be more possibilities. Which is true.
I don't know, just linking what was posted in the other thread. I'll snip the link.
So it turns out that the most spectacular post quoted there is actually a GAF post. Some very intriguing stuff, but I don't know if it's true. Especially the following fragment, which I'm not sure I've grasped completely (Link to the Beyond3D post quoting it):
Next, the magic happens: the cache scrubbers make it so that the PS5 never needs to split its RAM used by the GPU into two distinct pools (a buffer for GPU reading and one for writing). The claim is that the PS5 can therefore render 2x-3x the detail that XSX.
It sounds magical, but I can't disprove it or anything, so I wanted to ask some people with more knowledge in this thread about whether this is a realistic look at things (or if it is completely made up). And if it is realistic, wouldn't it have made sense for MS to implement something similar to cache scrubbers (or have they under a different name?) in order to have similar functionality? Hope someone can answer this!
Right off the bat, there seems in my eyes to be an oversight: the post waives away the 3.5 GB of RAM that the XSX has as wasted RAM, but I would think that in reality it would be used for less bandwidth constrained tasks (I've read that audio is a good example in the XSX articles). The 8GB pool of free memory attributed to the PS5 would be reduced for similar non-GPU tasks, so a better comparison number would be that same 5 GB pool (disregarding the argument of offloading the OS to disk for the moment).The Place That May Not Be Mentioned said:
Next, the magic happens: the cache scrubbers make it so that the PS5 never needs to split its RAM used by the GPU into two distinct pools (a buffer for GPU reading and one for writing). The claim is that the PS5 can therefore render 2x-3x the detail that XSX.
It sounds magical, but I can't disprove it or anything, so I wanted to ask some people with more knowledge in this thread about whether this is a realistic look at things (or if it is completely made up). And if it is realistic, wouldn't it have made sense for MS to implement something similar to cache scrubbers (or have they under a different name?) in order to have similar functionality? Hope someone can answer this!
Right. Or potentially LoD, mip levels, on textures.
I think that's the kind of stuff people talk about wrt 'ssds and visuals'. In the end both systems presumably have the same RAM for games, so once the camera -or the objects in the scene - settles down, and you don't have a temporal/dynamic component, they could converge on the same asset detail or whatnot. But there's potential for variance in the temporal behaviour.
That post is nonsense.
AMD RT work with CU and clock speed .
You can't say 52 CU is 44% better RT .
You have to use CU and clock speed to get amount the gap will be.
This is ignoring the impact of clock speed. Also Liabe Brave actually made a post about RT on the previous page. Be interesting to see how it all pans out.
NX Gamer: PS5 Full Spec Analysis | A new generation is Born
I guess the speed at which the GPU accesses the memory is defined by the memory speed so is unaffected by GPU clock boosts?
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And racing games are typically not very demanding to render, so there's more possibility to spend budget on RT without impacting the rest of the presentation.
Lockhart would also be rendering much lower resolution, which will reduce the calculations needed. Even if it's only 4TF as rumored, number of rays should be about 1/3rd of XSX. If resolution is only 1/4 (1080p vs. 2160p), there shouldn't be much problem. This rough number does seem to indicate lowered RT quality if Lockhart renders at 1440p, or if XSX is rendering below full 4K.
It's confirmed. The way Microsoft promoted their RT performance is by saying XSX can do 380 billion intersections per second. This number is amount of TMUs times clockspeed. (TMU is Texture Mapping Unit, of which there are 4 per CU.) This gives an exact figure of 379.6; doing the same calculation for PS5 gives a value of 321.1. That's 15% lower, the exact same gap as general compute...which makes sense, since it's dependent on the same two things, amount of CUs and clock.
In other words, if a PS5 game is 15% lower resolution, then it should have the same quality of RT. Or, XSX could have 15% better RT, but then the two games would run at the same resolution. (In general, logical terms only, of course; real results will differ slightly from game to game.)
The GPU operates on data stored in its local caches. When those calculations are done, the results are sent back to RAM and new source data is loaded from there. When the GPU clockspeed is high, calculations finish faster so you need to refill the RAM more often. But GPU clockspeed doesn't apply to RAM, which has its own invariant bandwidth. That means the windows where RAM will accept requests are farther apart, compared to the amount of math you're doing.
This is why people with technical know-how think the RAM bandwidth may be a limiting factor for both PS5 and XSX performance. The way both platforms might not be bandwidth-starved is if they can keep as much data in the local caches as possible, reducing trips to RAM. But also, AMD has worked to reduce bandwidth needs for the same amount of work by changing the architecture.
This may also be ameliorated by the fact that PS5 is likely to have more L2 cache per CU than XSX.
Neither platform will fully utilize the RAM available on what is directly in veiw, but if Cerny is right, there could potentially be more to work with at a given time with the right engine optimizations.
This is ignoring the impact of clock speed. Also Liabe Brave actually made a post about RT on the previous page. Be interesting to see how it all pans out.
NX Gamer: PS5 Full Spec Analysis | A new generation is Born
I guess the speed at which the GPU accesses the memory is defined by the memory speed so is unaffected by GPU clock boosts?
That's the sensical thought. It all looks good on paper, even for PS5. Execution with its games is another thing. We have to wait and see.
Still one of the best threads on Era in a while imo. It's super fun to learn about these consoles. I wouldn't call the conversation rotten just passionate. We all know these boxes are coming in with differing capabilities, exclusive games, and most likely prices. Unless money is no object, I think most people if they can afford a new console can really only afford 1 (and do justice to it by buying several games, extra controllers, etc). So although both are beasts, although both will get great games and services, the question 'which is best?' remains extremely relevant to anyone watching with purchase interest. Taking the 'both a great and equal' perspective is actually frustrating and not helpful. People need to decide where their $1000 is going this year and nobody wants to toss a coin to decide.
I forgot about the prefetch window thing. Yes, if you can get away with a smaller prefetch footprint on PS5, then there may be more memory available for your in-view, 'converged' visuals.
So to what extent that could result in a noticeable difference would depend on the game's ability to fill memory in a given view wrt its highest lods, whether that ever spills over the memory available on XSX vs the same memory on PS5 with a potentially smaller prefetch footprint, how much memory PS5 could actually save with a smaller prefetch window etc. Again, another game by game thing. (And of course there are other things that could affect available memory for what you're actually looking at at any one time on each system...).
Worldwide Studios' baseline hardware is PS5, and PS5 only. So they can work on games that fully utilise the SSD, Ray-Tracing, and overall architecture of the machine. The same cannot be said about Microsoft, they will apparently have Lockhart, and also PCs to target, and with that being said, do we honestly think they're going to have a minimum requirement of an SSD (at a specific I/O throughput) and RTX as a minimum PC requirement? Doubtful.
Does this really matter much? I mean, to be direct, does anyone ever choose a console manufacturer based on power? IMO, people who want power over other considerations build a gaming PC, not buy a console. The Xbone beats out the PS4 Pro as the most powerful console, and that hasn't done anything to prevent Sony from utterly dominating this generation up until Nintendo got the Switch out (talk about console power being a lesser consideration, there). Sony got the exclusives, Nintendo got the exclusives, and good exclusives sell consoles. I don't really care whether the next XBox or Playstation is technologically superior, and I don't think the market does, either. I'm going to buy a PS5, because I'm a fan of Japanese games and a lot of Sony first party franchises, and backwards compatibility means I don't need to keep my PS4 Pro when the change comes. The power of PS5 vs Xbox doesn't even come into it. And if Xbox actually gets some decent exclusives next gen? Maybe I will get one to replace the Xbone I keep around for backwards compatibility, but Microsoft needs to offer me good games I can't get elsewhere, not more powerful hardware.
There will likely be profiles for devs to choose from, if their game is GPU-bound, they can enable dynamic power to give it a boost. Otherwise they can pick a static 3.2 Ghz + 2200Mhz GPU or something in that vicinity.
This completely exonerates Mark Cerny. Thank you.
In theory, Cerny would've had to think about where the biggest bottleneck was. 4k is 225% the pixels of 1440 . So a GPU running at 5.3 TF can render the same stuff @1440p as a 12 TF XsX @4k (Hi Lockhart!). If Cerny thinks games will look identical on both consoles thanks to dynamic resolution and diminishing returns on picture improvement, he really has no choice but to put money on SSD customization.
What I am super curious about is what is the cost of the proprietary chips dedicated to making the SSD reach its potential (Kraken codec, etc)? Would they, combined, cost the same as the difference between a 36 @2.2Ghz and 52 CU @1.8 Ghz APU?
While my dream scenario would have been for both machines to have identical specs, I think this is the second best scenario. Each 3rd party game will now run on consoles that are pushing the limits for both slow and wide AND fast and narrow architectures. All games should find a loving home, whether they love Mhz or CU counts.
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_rogame has made so many ignorant twits in general that people should be questioning how much he understands about this stuff. And Sony hasn't demonstrated pretty much anything at this point except for the Spiderman loading times demo last year only behind closed doors. Only thing that Mark Cerny stated is that he's becoming bullish on RT performance based on the ray traced games he's seeing and their performance.
44% more RT hardware is still running at a much slower frequency (1.8 vs 2.23GHz). The two effects needs to be considered together pretty much as with the teraflops metric.
Thinking the performance gap in ray tracing will be 44% because there are 44% more CUs is like claiming that XSX has 44% more teraflops based on CU count alone. Nonsense.
Thank you Dictator for the information you've provided in this thread. It's hard to muddle through the console warring and fanboying over the past number of days and I appreciate the clarity you've brought.
The attacks against you personally and the claims of ulterior motives are pathetic, but sadly, predictable. Hope you won't let that keep you from posting regularly for those of us that enjoy reading your posts.
The attacks against you personally and the claims of ulterior motives are pathetic, but sadly, predictable. Hope you won't let that keep you from posting regularly for those of us that enjoy reading your posts.
That alone is such a damn blessing paired with an insane I/O throughput unlike anything seen before in video games development as a baseline. First party will 100% make heads spin with next generation as well. Cannot freaking wait honestly, because it will absolutely be a rising tide situation. Everyone including 3rd party will step their engines and games up once again. It shall be glorious.
Yes, compression improves real throughput above the raw transfer speed. But as I said, we do know what Microsoft's compression can possibly do--they told us! They said real transfer speed with their compression is 4.8GB/s, not 2.4GB/s. Similarly, Sony said real transfer speed with their compression is 8-9GB/s, not 5.5GB/s. So with compression, Sony is currently between 67% and 95% faster, not 129%.
Yes, a difference in RT could be visible, because XSX has more resources available. But if so, those resources will not be available for other rendering tasks. So the game might run at the same resolution and other graphical settings, but with ~15% better RT on Series X. On the other hand, if the extra power of XSX is used to further improve resolution, then there's no longer any extra to do additional RT. So the game would have the same RT settings as PS5, applied to a slightly more detailed image.
You have to keep in mind that, while XSX is more powerful, the gap between the two machines is the smallest we've seen in decades.
Right, that's throughput though... however you have to remember that BCPack can possibly compress textures far better than Kraken which is more general purpose. The majority of game data is texture data... If MS' compression+BCPack allows for more data to be stored in the same amount of RAM then MS can require less bandwidth to transfer the same amount of data.
I appreciate you wading through the muck of a console war in full swing, but as somebody who isn't technically savvy I must admit I'm still having a hard time parsing your interpretation with how the PS5 CPU and GPU will perform and why you believe devs will have to make a choice. If you respond feel free to get as technical as you'd like but can we clear things up?
1. Do you believe the PS5 will be able to run the CPU and GPU at their max frequencies simultaneously for sustained periods and/or generally the majority of the time when needed?
2. Just how much of a constraint will the variable frequencies of the GPU/CPU be for developers to work with, especially if the answer to the first question is that it can run both at or very close to max frequency most of the time?
It's these two questions that I'm getting conflicting info on and every time I read somebody say, "thanks poster x for clearing that it!" I feel like I'm missing something. My interpretation of what Cerny said is that the PS5 can essentially utilize the 10.28 TF power of the console most of the time if needed, that the CPU and GPU can both match their capped frequencies at the same time (because they designed the cooling system with this in mind and worked backwards). If this isn't true, then I'm not sure what Cerny could have possibly meant.
But that's just talking about the compression they've already mentioned.
I mean, there'll be texture encoders used in PS5, compression formats that are gpu friendly. Such are already used in games shipping today on existing consoles. Maybe some will be wrapped in kraken, maybe not. Maybe Sony will have decode hardware for them, or maybe not. But gpu friendly texture encoders are, afaik, pretty light on decompression time anyway. Anyway, I definitely don't expect kraken to be some kind of universal panacea for compression on PS5, there'll be other tools too, even if they don't all come with (or necessarily need, vs general compression schemes) hw acceleration.
To what extent the different stacks amplify different data types is... up in the air. But I say all this say, I expect both stacks to be very good here.
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I agree that people need info to make a major purchase decision, but 99% of the market don't need the info in this thread to make a purchasing decision. Since generations began, power has never been a determinant. The info people really need is price and games. People were willing to buy ps2s, 360s, and switches at record pace despite power concerns from online enthusiasts.
All compression efficiencies are already included in the real world numbers. Remember, the actual throughput of the physical hardware is 5.5 or 2.4GB/s. More than that is literally impossible to shove down the connection. Therefore, when metrics are given that "exceed" that, it's meant to indicate what size the data would be if uncompressed. That is, 4.8GB of data comes off the SSD, is compressed down to 2.4GB, and passes to RAM in one second. On PS5 the compression seems to be less efficient, so 4.8GB off SSD becomes ~3.1GB to pass to RAM. However, it can also move faster through the pipes, so the lesser compression is more than made up for, and the same 4.8GB is transferred more quickly.
That's actually one of the benefits of the XSX architecture, its features are compatible with Direct X 12 Ultimate. And Lockhart is designed with all the features of XSX, just a lower resolution target.
Right... but if MS' compression is better... it can fit MORE data in the same amount of RAM. In your example Sony has filled up 3.1GB of RAM in 1 second, where as MS only has filled up 2.4GB... for the same amount of data. This gives MS more memory to work with. If they can fit more data in the same amount of RAM.. then they can reduce the amount of pressure streaming in new data from Storage to RAM.
It's not JUST about the throughput... but also how much data you can actually store in the RAM. Of course that's assuming Sony doesn't ALSO have more usable RAM available to developers.
I'm not saying that's going to make up for the ~2x difference between them... but if MS can store more data in RAM.. it will help mitigate some of the difference.
Hey everyone, I decided to join the thread after seeing a lot of people having legit answers to two very complex systems with few reliable information to go on and a lot of disinformation from many parties. I quickly wanna ask Dictator from DF if his sources can confirm Sony's use of a RDNA2 APU, because the stance of people online, tech journalists and viewers, especially in France, is to say Sony doesn't actually have RDNA2 silicon in the PS5. Basing this on DF's twitter posts as quote. What is your take on that ? Here is the quote using a reddit post as reference (DF twitter posts are quoted by this user as well).
The weird thing, from what I gathered, is that the AMD event actually confirmed the use of RDNA2 in consoles, with ASICs for RTRT: AMD financial analyst day 2020 but indeed Sony's website (back from October 8th, 2019) quoted the console using RDNA, Navi Google translation of Sony's announcement with console specs. Interestingly enough, the website also announces 8C/16T AMD CPU, which was not mentionned by Mark Cerny, like Variable Rate Shading. I would like to point out a very wrong mentality people have had of either confirming or denying specs from MS or Sony announcements because of something being not mentionned. ie "Sony did not mention VRS and did not specifically mentionned hw-accelerated RTRT, so it MUST not be RDNA2" or also "Sony did not mention SMT, therefore it MUST be only 8 threads". Yet AMD and Sony both confirmed using RDNA2 and hw-accelerated RTRT. Keep in mind the old Sony post dates from before any "Big Navi" announcements, and "Big Navi" is still part of the "Navi" family and it would make no sense to confirm or deny it at this point.
A quick sum up of what is definitely confirmed for both consoles, not sure to exist, and definitely out of the question is TBD for me in a few posts.
I'd also like to address people's takes on the performance delta between the two consoles, because I do this for a living and I'm getting uncomfortable seeing people push aside bottlenecks, or invent new ones to justify one console dominance over the other. My first take is this: the new XboX has a more powerful GPU than the PS5, period. Now the real question is: how much more powerful ? And for how much more money ? The second question, not to be answered until prices are announced (but should be at least 100$ over a PS5, both consoles being sold at a loss anyway).
Now if I want to convince you about bottlenecks, I have to take an example, mainly with gaming on a PC, that shares the same Zen2 CPU architecture as next gen consoles, and relies on either Nvidia's Turing or AMD's RDNA1 GPU architectures. Regardless of who makes your GPU or CPU, if you play games, you'd likely see:
The weird thing, from what I gathered, is that the AMD event actually confirmed the use of RDNA2 in consoles, with ASICs for RTRT: AMD financial analyst day 2020 but indeed Sony's website (back from October 8th, 2019) quoted the console using RDNA, Navi Google translation of Sony's announcement with console specs. Interestingly enough, the website also announces 8C/16T AMD CPU, which was not mentionned by Mark Cerny, like Variable Rate Shading. I would like to point out a very wrong mentality people have had of either confirming or denying specs from MS or Sony announcements because of something being not mentionned. ie "Sony did not mention VRS and did not specifically mentionned hw-accelerated RTRT, so it MUST not be RDNA2" or also "Sony did not mention SMT, therefore it MUST be only 8 threads". Yet AMD and Sony both confirmed using RDNA2 and hw-accelerated RTRT. Keep in mind the old Sony post dates from before any "Big Navi" announcements, and "Big Navi" is still part of the "Navi" family and it would make no sense to confirm or deny it at this point.
A quick sum up of what is definitely confirmed for both consoles, not sure to exist, and definitely out of the question is TBD for me in a few posts.
I'd also like to address people's takes on the performance delta between the two consoles, because I do this for a living and I'm getting uncomfortable seeing people push aside bottlenecks, or invent new ones to justify one console dominance over the other. My first take is this: the new XboX has a more powerful GPU than the PS5, period. Now the real question is: how much more powerful ? And for how much more money ? The second question, not to be answered until prices are announced (but should be at least 100$ over a PS5, both consoles being sold at a loss anyway).
Now if I want to convince you about bottlenecks, I have to take an example, mainly with gaming on a PC, that shares the same Zen2 CPU architecture as next gen consoles, and relies on either Nvidia's Turing or AMD's RDNA1 GPU architectures. Regardless of who makes your GPU or CPU, if you play games, you'd likely see:
- game files imported from your SSD into RAM by your CPU, when a game starts all the way to the main menu
- after a load time that spawns you into a level, whether the game is open world or not, assets that need to be drawn are either in CPU RAM or in VRAM close to your GPU. Not everything is readily available, but you can move around and not access massive amounts of assets on the SSD or the slowest memory.
- Regardless of what people think, the CPU does very little work himself, but he resolves calls and fetches data from an SSD, RAM or within its cache, and directs all the data and instructions over to the GPU, through a PCIe interface (on Zen2, it's 16GT/s on a PCIe 16x connector, 2x that of PCIe 3.0).
- your GPU exists for two law's in particular, amongst many more: Amdahl's law and Dennard scaling. The first can be summed up
as follows: "you'll see good scaling in the work that is the most parallel, but always to a point, and you're limited by what's not parallel". The second law used to work in pair with Moore's law: if transistor density goes up 2x each year, this means transistor dimensions in both dimensions are ~0.707x of previous generation, increasing their frequency by about 40% and requiring less energy, less voltage to keep the same power density. Which is no longer true: frequency doesn't go up as planned, and power densities of high frequency chips is not sustainable. Hence we can make very small processors, grouped together, that do fewer tasks, slower, but in parallel. - so if you aim at high framerates, there is a latency constraint, it is to output a new frame every 1/frequency of your refresh rate. At 60fps, it's 16ms, 120fps is 8ms and so on. If you work on 1080p images, you work with ~2M pixels, in 1440p ~3.7M and ~8.3M in true 2160p. You would think at that point that the CPU and GPU both are very critical when resolution increases, actually it's not true, while the GPU works on larger data and more pixels, the CPU is only redirecting more work to the GPU, and has more time to slack than before. Also because it now takes longer for the GPU to work on frames. Benchmarks show the higher the resolution, the less CPU performance and frequency matters.
- because of those latency constraints, it becomes critical to only put in VRAM what's really useful, and keep in RAM what is needed reasonnably soon, but not that soon. VRAM is used to store assets, store results, GPU compute units also have caches to access work resources faster, and time their access to memory so they don't stop ("stall") when they have no work, waiting for resources or waiting for another compute unit to be done.
- RAM is used to store assets that were recovered from the SSD, the more RAM you have, the less it becomes relevant to rely on very fast SSDs, apart when you exceed RAM capacity. Because you can store critically needed assets and textures in VRAM, you don't always need to wait for data to travel from RAM to VRAM through the PCIe connection, and you can use VRAM as a buffer. Similarly to RAM and SSD, the more VRAM you have, the less PCIe transfer speed matters, and the less you have, the more you'll see a difference from going PCIe gen 3.0 to 4.0 (benchmarks on this can be found online).
- All of this should help realizing that SSD really isn't really a determining factor in framerates. Perhaps older HDD were responsible for stutters in large complex environments, but thanks to caching and complex memory hierarchies the only thing they slow down is loading times. Also, it becomes less of a relevant point of comparison the more the base reference is powerful. That's simply because of diminishing returns.
- scaling isn't fantastic in GPUs. With Turing, the 2080 Ti use 41-47% more CUs than a RTX 2080 /Super. Yet you only see a 25-15% lead in framerates, and like I mentioned before, that lead extends to 35% when playing in 4K. Because larger workloads will see higher utilization of that GPU, better use of more parallel memory subsystem that's otherwise causing extra latency when worker groups are smaller.
- that's when you have quite enough VRAM (larger memory buses will also help accessing more data in parallel, meaning less time spent waiting for data, or stalling), the compute units on the GPU are well utilized (90-95% utilization or above). At that point you'll see GPU core frequency matters a lot..
- If your chip contains more workers, you can tolerate and accept lower frequencies accross all compute units. Unlike a CPU which gives a smaller response time to a very linear segment of code the faster its frequency is, a GPU has a latency constraint to comply to, regardless of frequency. However, having more CUs isn't a 1 on 1 relation to latency. Because all those workers consume power, and the network or crossbar to connect them all together likely consumes a lot of power, you can't offer to run them at as fast a frequency as a chip with less CUs.
- And this is very complex to understand: 52 CUs against 36 CUs for consoles means the biggest chip will heat up quite fast when running against a smaller chip, and this even if the frequency is lower. Power goes up linearly with frequency, and quadratically (square) with voltage. Now if you raise frequency, you also need to raise voltage, otherwise you can't sustain clocks and crash. A GPU like any ASIC is designed and optimized to run at a specific frequency range. Within that range, it is very efficient, outside of it, way less. For any chip, diminishing returns means you'll raise voltage too much to sustain clocks, causing the GPU to heat a lot. We have no idea how those Navi chips are tuned, and if >2GHz frequencies is efficient or not. Keep in mind AMD mentioned 1.5x the perf-to-watt over RDNA1, this means it's definitely not impossible.
- you might think heat does not matter, but any modern GPU includes management engines that will aggressively clock the GPU frequency down or up based on its operating conditions. fyi, Pascal and Turing GPUs drop clocks as low as 52°C and up. Same goes for CPU, no clock is ever constant. 105°C or 95°C for GPUs is when it starts to throttle hard and shutdown might happen (or very low clocks of a few hundred MHz). As far as throttle goes, your GPU or CPU might throttle when its Voltage Regulation Module is overheating (converting 12V to ~0.6-1.4V) or when a specific power limit in Watt has been hit (power throttle). Same goes for GDDR6 chips, if they overheat, either you clock down, or you get artifacts, then you crash.
- A big thing most people don't interpret properly: the difference in core clock speeds for PS5 and XboX iGPUs. To be fair, Sony did probably raise core frequency to catch up, but there isn't a case of "MS knowingly using lower clocks because they use a more powerful chip so they wanted to give Sony a chance" and there is no "Sony overheating and damaging their iGPU with aggressive clocks". Because the larger chip made for XboX uses a lot more CUs, and needs extra logic to route more data, wider controllers, (effectively wasting silicon for scaling's sake, and frequency's sake) it probably can't even clock to 2GHz anyway. Binning and yields being worse on a larger die also make it doubtful. In normal operating conditions, it is definitely not sustainable (if possible) to run at 2GHz or above for the XboX APU. If anything, I'm surprised MS expects to hold 1825MHz on such a massive chip. It seems more doubtful than to expect Sony not to be able to run 2.23GHz on their 36CU iGPU.
- I would expect a massive difference in RTRT performance as Dictator mentioned, again. Because CUs embed a RTRT unit, and they will be the main bottleneck when under a RT workload, they will make a lot of difference. See this patent for details on actual implementation and this RDNA1 whitepaper for details on RDNA1. I think AMD and Nvidia also know dx12 Ultimate(what MS said they'll use) and vulkanRT(what Sony may use) brings a more powerful RTRT platform to build games on. In any case you can probably expect close to a 2080 performance on boost mode on PS5, and definitely 2080 Ti performance for the XboX (TSMC N7P and 52 CUs is such a massive difference over a 5700XT that's 0.70-0.65x the performance of a 2080 Ti).
- MS claims of "fixed clocks" or "constant clocks": in a recent ad, it's been worded as "GPU designed to run at fixed clocks". First of there is no such thing as non-dynamic clock in any modern CPU or GPU, frequency will always be constrained by power, thermals and utilization. I'd expect raytracing instructions to lower clocks for any RDNA2 GPU, similar to AVX offsets on Intel CPUs. On the announcement by Mark Cerny of dynamic clocks, people panicked for wrong reasons, and people did not question MS's claim of constant clocks at the same time. Dynamic clocks is a good thing, it helps raise clocks when your system needs to, and lower it when it doesn't, so it can save thermal headroom for larger boost duration, or simply save power and APU lifetime. Both APUs should embed AMD firmware, and AMD Smartshift. This will automatically lower CPU clocks, or GPU clocks, (saving power and thermal headroom) and proportionally raise GPU clocks, or CPU clocks for up to 10% performance boosts. That's why dynamic clocks are a good thing.
- On the matter of power, people on r/AMD found out the PSU for the XboX series X is actually a 255W+60W PSU, with 255W expected to be the system wide power budget. If you look at reviews by GN or Hardware Unboxed (the most precise measurements made), you'll see 8C/16T Zen2 chips running at over 120W for >4GHz frequency, SMT On. Disabling SMT should save 15% of the CPU power budget for a low impact on game framerate (1-5% at lower resolutions), running the CPU at 3.5GHz or lower should also be quite efficient. Finally, the chip relies on TSMC N7P claiming a 10% efficiency gain at iso speeds, and the chip is monolithic so more efficient from centralized I/O in the same die as the core complexes and the iGPU. Based on this, I would not expect the iGPU and GDDR6 chips to have access to more than 200W of power, which is not a lot for such a large design at such a high frequency.
- On the matter of cooling, it is also not a lot of headroom for a chip of such design, that shares die space with a CPU with a 60-80W TDP, and shares its vapor chamber coldplate with 10 high-speed GDDR6 memory ICs. I've seen it is a 130mm fan that is used, not a 200mm. It will be tough to cool.
- I think it is weird to believe 2.23GHz clocks on a 36 CUs RDNA2 chip is odd on PS5 considering they have lower CPU clocks, when MS showcases such a massive chip as the XboX with 52 CUs and a 1825MHz clock that is fairly high considering they advertize "constant clocks" and a 16 threads CPU. Sony has not disclosed their cooling solution, but it's fair to say it will be as massive as the XboX's. The XboX should consume more power anyway.
- the PS5's SSD should not immediately provide any differences in framerates, but the cache scrubbers and coherency engine they mentionned, as well as MS's Sampler Feedback Streaming technology (see here) might provide huge gains in GPU performance and RTRT performance. AMD GPUs seem to have a real problem with overutilizing memory and stalling due to high VRAM utilization, anything that can compress memory or lower usage should lead to critical gains, especially in caches. Dictator do your sources have more on this ? it's the most relevant probably by now.
- Bandwidth, just like Teraflops, is a very bad measure of performance in computers. Indeed SSDs are very good because of low latency and not really because of bandwidth. People on PC like to run RAID0 setups of NVMe SSDs, performance definitely does not scale in games.
- This generation again, it's unlikely CPU performance will matter much, especially for targeted framerates and higher resolutions. Consoles also like to use a tuned quality compared to PC games, it's unlikely they won't tune for extra quality with RTRT, or 120 fps gaming with upscaled 4K. In that case, both consoles should be able to do it, consider the PS5 is likely having similar performance to a RTX 2080.
- I wish MS wasn't scared of opening about dynamic clocks and the use of SmartShift. People would understand if explained properly. Cerny might have not made it very clear.
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