Handbrake x265 encoding cpu doubt

[Sephiroth]

Does the power of the CPU (or entire pc) affect the quality of the video or does it only affect the encoding speed?
In other words, with the same settings do they get the same quality from both an i5 and i7 regardless of how long it took?

[sophisticles]

Does the power of the CPU (or entire pc) affect the quality of the video or does it only affect the encoding speed?
In other words, with the same settings do they get the same quality from both an i5 and i7 regardless of how long it took?

Just the encoding speed.

[KarMa]

There can be super minor differences between videos made on different CPUs, due to what type of instruction sets are supported on a given CPU. These differences are not even worth mentioning but I say it just to make the point that two CPUs might not make identical videos. Number of threads can also affect the final video, mostly slightly when talking about single digit # of threads. As sophisticles said, this is mostly a speed thing.

[sophisticles]

If you really want to get technical, the above is correct but the other side of this coin is that a faster cpu will allow you to use more aggressive settings for the same encoding speed, so it could be argued that in practical terms the faster cpu will give you better quality. Check out my review of Intel's SVT encoders:

https://forum.videohelp.com/threads/392544-Intel-SVT-HEVC-encoder-test

Check out Phoronix's benchmarks here:

https://www.phoronix.com/scan.php?page=news_item&px=Intel-SVT-Clear-Cascade-Lake

https://www.phoronix.com/scan.php?page=news_item&px=27-CPUs-AV1-SVT-Video-Encode

The Intel SVT family of encoders are heavily optimized for AVX2 and AVX-512 as well as multiple threads. Because of this, if you were to go from something like an i5 8400 to a Xeon Bronze 3204, which has a very beefy AVX-512 unit or a 9900k, in practice you would most likely use more aggressive settings while getting faster encoding speed and so you could argue that the faster cpu is giving you better quality.

It really depends on which way you look at it.