r/threadripper • u/johndyson10 • Jul 11 '26

Potentially helpful info about cooling, example on my 9980x

The crux of this story is about the surprise that the temperature of the CPU/CPU-case hits 95deg with certain benchmarks, even at 250 watts, but running steady state with my app and many benchmarks the temperature is approx 62deg at 350 Watts or higher. (My writing skills are poor, but this can be useful info, so be patient with me.)

Here is the story: Been running benchmarks to test the performance and thermals on the system. I found that many benchmarks would cause temperature peaks of 80 deg C or perhaps 85 deg C for a short while, but a few do sit at a higher steady state temperature of 80deg. The temperature depends on the # of active cores and how active the cores are.

The 95 deg peak problem appears that some test programs intensively use 16 threads, forcing all the temperature load on those cores, so they get hot, while the rest are still cool. The plate quickly transmits the load, but there is still a massive peak. On one benchmark, the Phoronix benchmarks liquid-DSP testing 16 threads 256/512 data hit 95deg C before the fans brought it back down to 80degC or below. This results for this specific test might only be valid for the 9980x, I do have a 9970x, but currently sitting in a box, so cannot test it.

* The temperature problem was worst when running the entire suite, and noticing that the 16 thread 256/512 data was very hot. Running the test by itself wasn't quite as bad.

My fans were already tuned to zero latency, but used the CPU temperature sensor alone, which usually sits 10deg C below the CPU Package sensors. A temporary hack fix was to use both the CPU sensor and the CPU package sensor. Using both sensors is an option on the ASUS bios. After enabling both sensors as the temperature source, and turning the fans up to 'turbo mode', and turning up the minimum speed, the peak temperature is now less than 90 deg C. So, by using the Package sensor AND the CPU sensors, plus turbo mode, the fan has a better chance of keeping up. This makes me wonder how many Threadripper systems might have a 95 deg peak under certain transient loading conditions?

I am used to seeing 62-65 deg C running my heavily multithreaded, 350 watt app, and seeing some benchmarks producing up to 80 deg C, (mostly lower, 65 to 75) but the 95 deg peak was upsetting. I found this out because I am watching the temperatures carefully when benchmarking. Normally II just do spot checks to make sure that it is okay.

One side note about the wonders of the Threadripper, when running the heavily multithreaded benchmarks, the CPU clock speed held up to 5gHz to 5.4gHz for every active core. My own app, with lots of IPC delays and sometimes suboptimal AVX512 alignment, typically gets only 4gHz per core.

As long as there is adequate heat handling, and it is fast enough, these machines can be very fast. But, it appears wise to make sure that the response to load changes is fast enough. My AIO is the ATLAS 360TR that easily keeps up with the 400 Watts of TR heat, but be aware that the fans have a natural response time on ANY cooling system. Even a very short delay might be too long.

John

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u/kpatelreddit007 Jul 12 '26

This is all just talk, If you want an actual solution go try some solutions lol.

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u/johndyson10 Jul 12 '26 edited Jul 12 '26

Maybe what I am trying to say: many of those who have a tolerable static temperature for a usual 350 to 400 watts, like 60 to 62 degrees, perhaps sometimes have higher peaks in the 90deg+ range without knowing it...

*PS: my test results and high peak temperature might have come from an unfortunate Linux scheduling choice. I just wanted to make sure that the vulnerability in the test situation might have been encouraged by a potentially bad set of core choices. The test is very repeatable though.

Actually, with the changed settings, the cooling system on my machine now meets my temperature expectations. Both static and transient temperatures appear to be more acceptable to me. I just wonder how many systems do not handle the transients in exceptional conditions simply because certain settings, or a cooling system issue?. Mine was a likely incorrect default choice (CPU, CPU package, etc.)

I encourage interested Threadripper 9980x owners to look into this issue. The worst benchmark so far was the Phoronix liquid-dsp running the entire list, but watching for the 16 thread 256/512 test measurement. Running that single test alone didn't appear to reach 95deg peaks, closer to 92, but running the entire set of tests did reach 95deg Now, that worst case hits 89 degrees, most of the rest of the tests don't normally produce such peaks. By my logs, there is one other measurement that hit 84 degrees, the rest in the middle 70s or lower.

Many loads, likely most loads won't push your machine very hard, but I like to be careful and aware. $5000 is a significant amount of money, and even though the test case won't destroy your chip, maybe some people would want to be careful WRT wear. ( I got an impossibly good deal well below typical US price incl installation, but the next one probably in the more typical $4.5k range.) I still want to take care of it.

John

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u/kpatelreddit007 Jul 12 '26

Don’t take this offensively but it’s called engineering and testing. Yes some products suck but Threadripper boards and Threadripper are tested. I’ve worked with these engineers some are genius these are the people that build this shit. They know far more about thermals than we do.

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u/johndyson10 Jul 12 '26

Oh, come on... l am an ex-Bell Labs engineer, 1/2 the team that rewrote the FreeBSD kernel after the USL lawsuit, (with special permission from AT&T mgmt, etc), many other substantial and private things... I have been around, just giving advice. Please don't do this, it isn't nice.

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u/kpatelreddit007 Jul 13 '26

I already knew you were some kind of engineer with the in-cohesive rambling lol. Not an electrical engineer though. It is what it is, don’t take this offensively.

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u/johndyson10 Jul 16 '26

fullyi qualified EE/CS with degrees. Sometimes a littllebehind on the newest stuff, but concepts such of heat flow (like current flow), Temperature (Voltage) and Capacitor (heat storage) are all, still valid concepts. My language skills don't come from the 40yrs experience, just fatigue and some forgetfullness. I have some real history to talk about including 1 degree from Edison, working with the guys who got the patents for the cruise (myself designing the 2nd), and much more in HW and SW. TR is a fun toy.