C4D not using full CPU frequency

[grimm]

Hi there,

I wonder why C4D with Corona does not use full cpu frequency? When I try corona benchmark or cibench it is using full potencial of cpu. When I turn off Adopt thread priority and Lower process in C4D preferencess everything behaves the same way.
Do you have any experience with this please?

[TomG]

What hardware, what version of C4D, which OS, what version of Corona? :)

[grimm]

R21, Corona 5 hotfix, WIN10, i9-10940X.

[grimm]

But it does not matter, it behaves the same way on AMD cpu.

[TomG]

Well, it may matter, as it doesn't happen here (CPU usage is 100% when rendering). Some screengrabs showing your results could be useful, as could info on whether this is one particular scene, all scenes, etc.

[grimm]

Windows will show 100% usage. Try for example HW monitor utility. It will show also frequency of each core and temperature during rendering or benchmarking.

[grimm]

Here are to screenshots each with different frequencies, one from rendering and another from cinebenchmarking.

[houska]

This looks like automatic underclocking performed by the CPU itself due to use of the AVX instructions. Without them, you might have a higher CPU clock rate, but less effective floating-point calculations, so even with lower clocks, there's a good chance your CPU is doing more work because of the specialized instructions. Don't be bothered with it as long as you're getting good performance in terms of noise converging fast and as long as all your cores are utilized at 100%

[grimm]

It is 1000 Mhz difference per each core.

[houska]

This is strange, because it's 1000Mhz difference only for two cores. The rest of the cores shows only a difference of 400Mhz. I'm looking at the processor specification here: https://www.intel.com/content/www/us/en/products/processors/core/x-series/i9-9940x.html and it looks like the maximum TurboBoost frequency is 4.5Ghz, so those 4.8Ghz look as some mistake.

[maru]

It is 1000 Mhz difference per each core.

Sounds plausible: https://www.anandtech.com/show/11544/intel-skylake-ep-vs-amd-epyc-7000-cpu-battle-of-the-decade/8