CPU temps suddenly spike after about five to six minutes of Prime95

[Godofmosquitoes]

Hi.

I have a strange issue with my CPU, after I took it out and put it back in, for a change of cooler and thermal paste.

I changed from the Thermalright Le Grand Macho RT to a Corsair H80i V2, and from Kryonaut to MX4 thermal paste, to check out if there was a performance difference. However, now, regardless of which combination of cooler and paste I use, my CPU runs hot after a few minutes of stress testing. Before changing the cooler, I had the Le Grand Macho RT on, with Kryonaut in between.

What happens is that I start Prime95. The temperature then rises quickly, but settles at about 78 degrees C for the package, and just below for the cores. These temperature levels are stable in the beginning. However, after about five to six minutes of stress testing, my CPU temperature suddenly climbs, and both package and cores easily find themselves in the range between 95-100 degrees C.

I'm not certain if I had used too much Kryonaut with my initial spread, as it was rather thick, and I used their own spreader to do it. However, I cleaned both CPU and coolers very thoroughly. It is as if something suddenly reaches boiling point in the CPU, and everything gets very hot.

Anyone might have an idea what might cause this?

[Chino]

Godofmosquitoes wrote:
What about something like the EKWB EK-XLC PREDATOR 360, if I can still get my hands on such a set?

I own the Predator 360 and it really is an awesome AIO. However, EK will be releasing an updated version of their Predator AIOs so it's worth the wait. 🙂

[Godofmosquitoes]

Hmmm. It seems as if the latest version of Prime95 puts an insane amount of stress on the CPU. Way beyond any other benchmarks. And that this is the cause of my temperature woes. Running ASUS' own Realbench stress test for instance, my temperatures comes nowhere near what they do in Prime95. In fact they're very comfortably under 80 degrees for all cores.

[Zka17]

Yeap, that's why serious people don't use Prime95... 😛 It is not a real world testing, the only thing you can find out running it is that your system can or can not run it - then your system will crash easily when you open a web browser...

[JustinThyme]

My .02 not that it counts for anything.......
Prime 95=CPU heater, nothing more. If you want to test stability with real world scenarios try the realbench on the ASUS download page or AIDA 64.

Always after a fresh install it does take time for expansion and contraction to settle in. Give it some time.

If you are as anal as I am about temps follow these steps in order 100%
1) remove AIO
2) open trash can lid
3) deposit AIO in said trash can, do not remove
4) order custom loop and install

Delidding helps tremendously on some CPUs, others its not worth the risk.

[Godofmosquitoes]

JustinThyme wrote:
My .02 not that it counts for anything.......
Prime 95=CPU heater, nothing more. If you want to test stability with real world scenarios try the realbench on the ASUS download page or AIDA 64.

Always after a fresh install it does take time for expansion and contraction to settle in. Give it some time.

If you are as anal as I am about temps follow these steps in order 100%
1) remove AIO
2) open trash can lid
3) deposit AIO in said trash can, do not remove
4) order custom loop and install

Delidding helps tremendously on some CPUs, others its not worth the risk.

Thx for the advice. I went back to my Thermalright Le Grande Macho RT, after finding out Prime95 was to blame. Returned the H80i V2 to the store. I did an 8 hour stress test with ASUS Realbench 2.54, with my CPU at 4.2 GHz. It completed with no errors, and the hottest any CPU core got at any point was 85 degrees C. Which should be below the temps where the cores start to degrade, I have been told.