Boost mode on pro uses half the CUs, but the clocks are still running at native speeds for the GPU and CPU. We still don't know how PS5 will handle boost mode, but PS4 Pro and PS5 do have the same number of CUs so maybe that won't be an issue anymore.The way pro functions where it shuts off half the gpu to work for non-enhanced titles. I imagine by default, PS5 will do the same and also downclock CUs. Then, in boost mode, it will clock up but not increase CUs.