Quote:
Originally Posted by Stephen R. Savage
It's actually not so bad at higher frequencies, because each 100 MHz increment saves a lot more power, compared to 2.5 GHz server SKUs. i9-7900X can reach 4.1-4.2 GHz AVX-512 frequency with an aftermarket cooling solution.
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You can reach that if you boost the power you give the CPU, but unfortunately that also boosts the power outside of AVX512 mode, making your CPU overall less efficient. The integrated voltage controller has no option to increase the core voltage only in AVX512 mode, unfortunately.
But this is probably going a bit off-topic for X265.
I would've thought the X265 people already learned the down-clocking lesson with AVX2 though, where they experienced the same effect - fancy instructions that made the overall encode slower, especially on server systems, due to clock changes.