Not a duplicate of related post as this is a new setup, no dust, high performance cooler, ...

Hi, I put a beQuiet Pure Rock on a 7700k CPU in a workstation and the CPU has an odd temperature behavior. Usually, they slowly go up if you stress it with 100% load and then have some form of delay before hitting the idle temperature again. This makes sense on any level. Going up, the temps take a while to hit peak, the same for going down. But What I am observing in this machine is very odd and it gets me a bit worried.

CPU load and heat

The first rise was caused using a stress -c 2 on linux. The second using a stress -c 8, so stressing all 8 virtual cores. As you can see, the temperature rises and falls within the same second from 35 to 80 degrees. I just cannot imagine this is physically possible. What could cause this?

The cooler was applied using the factory applied thermal paste and it's sitting firmly on the CPU. There are 2x 120mm intake fans, 1x 120m outtake and one 120mm on the cooler itself.

Could it be an issue with how I applied the cooler on the CPU? Is it maybe not properly on the CPU? I can imagine a small gap in between the CPU and the cooler could lead to an almost non-existing heat transfer, but then why is my CPU idling around 35 C at 20% load but without overheating? Without any cooler it shouldn't be able to even withstand that little load should it?

Another idea I had was the Mainboard. It is a "GA-Z270X Ultra Gaming" as this had NVIDIA SLI support (the machine is meant for NN experiments). Maybe the motherboard does something to the CPU data? I haven't overclocked or anything like that so I am unsure what might cause this.

  • I very much doubt it’s firmly on the CPU, because otherwise this wouldn’t be happening. It’s probably just stuck somehow, making it appear firm. – Daniel B Aug 12 '17 at 13:11
  • I rechecked, it's properly on there. I could buy some additional paste and reapply it with a clean tube of paste. – pascalwhoop Aug 12 '17 at 16:39
  • I reapplied some thermal paste (grizzly something) and it had a 5 degrees temperature drop. Now after having been abroad for a few weeks and coming back home to a cooler autumn weather in Germany, the temperatures are more sane. The temps jump to 65 and then creep to 70 but stay there, another 5deg decrease. – pascalwhoop Sep 23 '17 at 19:56

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