The PlayStation 5's method for SoC boost allows for dramatic increase in GPU clocks much higher than PCs, no matter the ambient temperature
According to the PlayStation 5's just-announced specifications, the 8-core 16-thread AMD Zen 2 CPU can boost up to 3.5 GHz while the custom RDNA 2 GPU can boost up to 2.23 GHz. PS5 Chief Architect Mark Cerny said these are "capped speeds". The PlayStation 5 will not boost in the same way as do regular PC CPUs or GPUs. Regular PCs and even the Xbox Series X boost based on available thermal headroom. Therefore, in places where the ambient temperature is high, one can expect throttling and loss of frame rates.
In case of the PS5, however, things are a bit different. The console is given a certain power limit based on the cooling system. Essentially, the SoC runs at a constant power, but the frequency varies depending on the workload. According to Sony, this ensures that "all PS5 consoles process the same workloads with the same performance level in any environment, no matter what the ambient temperature may be."
The PS5 looks at the overall activity the CPU and GPU are doing instead of just temperatures. To account for silicon differences, the PS5 decides on the ideal boost clock based on a "model SoC", which is sort of a reference point for every PS5. Cerny notes that the CPU and GPU do not always run at the "capped clocks". The PS5 also uses AMD SmartShift technology to send unused power from the CPU to the GPU for that added graphics boost.
This approach to boost means that the GPU can hit speeds way higher than what is traditionally seen in the PC space allowing for extracting the maximum performance from the available 36 compute units (CUs). However, developers need to ensure to keep power consumption spikes at a minimum so as to not bring down SoC clocks.
Details of the actual cooling solution used are reserved for a future teardown.
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