- Nov 14, 2011
Some very cool stuff in here. Only 128-bit FPU on the PS5's Zen2 cores?!
For Scarlett, it is actually the CPU that becomes the limiting factor. Using AMD’s high-performance x86 Zen 2 cores, rather than the low power Jaguar cores from the previous generation, combined with how gaming workloads have evolved in the 7 years since, means that when a gaming workload starts to ramp up, the dual 256-bit floating point units on the CPU is where the highest thermal density point happens.
In this slide shown, although it doesn’t indicate what sort of workload is in play here, whether it is an active game or a power virus, Microsoft is showing 87.4ºC at the hotspot on the CPU side, while the GPU only has a 80.9ºC hotspot. Now this also comes down to the frequency choice and design point of the hardware, and finding the right balance between CPU power, GPU power, and overall thermal characteristics and acoustics.
I don't know about that. 256 bit vectors are used for physics calculations and particle effects in PC games by physics engines. Do you remember Ageia PhysX PPU? P4 and Athlon CPUs were so weak back then they couldn't do the calculations for cloth simulation at acceptable frame rates. Nowadays, modern CPUs can actually run cloth simulation faster than GPUs thanks to a new class of physics engines that have been built from the ground up to exploit wide vectors, SMT and multicore CPUs.256 bit vectors are pretty useless for games and code that can make use of it can usually also executed faster in GPU. So cutting unnecessarily FPU and replacing it with something more useful in console SOC is pretty logical thing to do.
CPU supports 256 bit native instructions that consume a lot of power
these are great here and there, but presumably only minimally used
if we plan for major 256 bit instruction usage, we need to set the CPU clock substantially lower or noticeably increase the size of the power supply and fan