What is your CPU temp while rendering?

[John.McWaters]

I'm curious what the temperatures are of other users' CPU while they render. This thread can also discuss cooling as well.

I have a 3900x, and it sits between 73–74 celsius while rendering. When it denoises, it shoots up to the low 80's. Is that normal?

It's being cooled with an Noctua NH-D15. I know the difference between AIO coolers and and air coolers for gaming is minimal. Does anyone know if the same goes for rendering where the CPU is at a high utilization rate for hours at a time?

[Nejc Kilar]

I've got a dual Xeon 2696v3 workstation that has dual NH-U14S cooling them. Fan speed is at around 80% when rendering but it surprisingly isn't that loud - it is clearly audible though. The temps max out at 64c if I'm doing concurrent GPU rendering otherwise they stay just below the 60c mark.

Looking at the specs, the max "allowed" temperature for these CPUs is a bit lower than other Xeon CPUs of the time at around 76c. I keep forgetting whether that is the max max or just a max for the turbo clocks to stay turbo.

Point being, each CPU generation can be different. Typically your max temperatures are specified in the manual, or on AMDs website in your case, and generally you want to stay good deal below that. If I recall correctly most CPUs tend to operate up until 90c before they start running into severe downclocks and the like. For longevity sake though, and especially since you are probably rendering more than an average gamer games, I'd personally probably like to keep CPU temps below mid 70s. The new Threadrippers are behemoths in every sense of the word and my thinking is, anything mid 70s and below is probably cool. Pun intended :P

Wonder what other folks think :)

edit:
Just noticed you have a 3900x. I think you could probably go lower with the temps there by either investing into better cooling or upping the RPMs but at the same time I think that temperature is "fine" too. I do think its on the warm side and I'd probably try to push it below 70c but I don't think you need to overly worry either.

[Juraj]

It's not on warm side at all. In fact, those are spot on temps for this CPU.

Discussing temps is not very precise since it's influenced by way too many factors. Some people have room ambient of 18C (UK-all year), and some 28C (South without AC units). This makes massive difference.
Closed cases (Like Fractal Define series) vs Mesh cases (like Meshify) can make another 10 C difference.

That's two factors that already swing temps in range of 20 (!) C alone.

Further, people assume it's based on amount of cores, which it is not. It's based on surface area & TDP. That is why massive 64-core Threadripper will shoot only up to 65-70C because the heatspreader divides 280 Watts over 8 chiplets, compared to 24-core 3960X which divides the same 280W only between half as many chiplets, shooting easily above 80C like nothing.

Highly parallelized and demanding instructions (like AVX-512 for example) will increase the CPU load despite the Task manager showing 100perc. utilization between rendering and denoising.
So denoising is far more demanding than rendering itself and will increase temps easily up to 10C.

That's why we have so many threads where people's PC are stable 98perc. of time but shut-down on occasion :- ). There has to be safe margin.

Average AIO coolers have jack-shit improvement over NH-D15 or NH-U12a. When they do due to more powerful fans, they are also much louder.  You can also put 2000 RPM high-pressure F12s Noctua fans instead of 1200/1500 RPM A15s and you will get same performance increase, if you are ok with 40 dB.

TL:DR: Your 3900X are fine.

[John.McWaters]

It's not on warm side at all. In fact, those are spot on temps for this CPU.

Discussing temps is not very precise since it's influenced by way too many factors. Some people have room ambient of 18C (UK-all year), and some 28C (South without AC units). This makes massive difference.
Closed cases (Like Fractal Define series) vs Mesh cases (like Meshify) can make another 10 C difference.

That's two factors that already swing temps in range of 20 (!) C alone.

Further, people assume it's based on amount of cores, which it is not. It's based on surface area & TDP. That is why massive 64-core Threadripper will shoot only up to 65-70C because the heatspreader divides 280 Watts over 8 chiplets, compared to 24-core 3960X which divides the same 280W only between half as many chiplets, shooting easily above 80C like nothing.

Highly parallelized and demanding instructions (like AVX-512 for example) will increase the CPU load despite the Task manager showing 100perc. utilization between rendering and denoising.
So denoising is far more demanding than rendering itself and will increase temps easily up to 10C.

That's why we have so many threads where people's PC are stable 98perc. of time but shut-down on occasion :- ). There has to be safe margin.

Average AIO coolers have jack-shit improvement over NH-D15 or NH-U12a. When they do due to more powerful fans, they are also much louder.  You can also put 2000 RPM high-pressure F12s Noctua fans instead of 1200/1500 RPM A15s and you will get same performance increase, if you are ok with 40 dB.

TL:DR: Your 3900X are fine.

Juraj,

Thank you for the detailed reply!

Do you know if a CPU will degrade over time due to hours spent rendering? Or is that only if you're pushing it beyond it's comfortable temperatures?

[Juraj]

Under stock settings, it might degrade a bit, but unless it was somewhat faulty chip, it will simply last 15 years instead of 20 let's say :- ). If the CPU didn't fail in first month, it probably never will.
(Can't be said the same about motherboards with their very questionable quality control unfortunately).

It does degrade when over-clocked (mostly with old-school method of fixed voltage which doesn't apply much to AMD chips). AMD chips supply high voltage only on low current, so when CPU isn't utilizing all its cores. Rendering does utilize all cores and the CPU will smartly lower the voltage quite a lot (and lower the frequency as well).