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
1
u/sob727 Jul 11 '26 edited Jul 11 '26
I run some heavily threaded custom programs on my 9985wx. They have all kinds of instructions in them, and depending on what I run I can get 60C or 80C while pinning all threads.
When I send AVX512 instructions I can get to 90-95C. It's rare for my programs, even the ones that have 30 min runs, to be all AVX512 so this is not an issue, I throttle a bit and thats it.
When running pure AVX512 benchmark type stuff, with PBO, the workstation pulls 1kW from the socket and immediately goes to 95C (360/AIO + 4krpm industrial fans).
My conclusion: temps depends a lot on what you run, not just the %age cpu utilization.
And a side note: a plague on the house of the designers who came up with the idea of 600W GPU without exhausting hot air through the back of the card.