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

Godofmosquitoes
Level 7
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?
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14 REPLIES 14

Chino
Level 15
A i7-6950X running Prime95 is too much for those heatsinks to handle. The temperatures you are experiencing looks reasonable.

Godofmosquitoes
Level 7
Before I replaced the cooler, the cores would lie at about 79 degrees all the time, occationally spiking to 83 :S

HisEvilness
Level 7
Could be that the readings were off before changing the TP and HS/Cooler.
I get different numbers on different utilities for my PC some show a higher temp then others.

Zka17
Level 16
What is happening is that at cold start those coolers can sort of handle the heat load, but as soon as they warm up, they become inefficient... simply they're not enough for that CPU.

LiveOrDie
Level 11
You will need a custom water loop for overclock any CPU with more than 8+ cores, mild overclocks will be fine but it will all depend on your core voltage 1.22v on load on a 10core cpu on a air cooler will not be able to handle it for long periods of time.

LiveOrDie wrote:
You will need a custom water loop for overclock any CPU with more than 8+ cores, mild overclocks will be fine but it will all depend on your core voltage 1.22v on load on a 10core cpu on a air cooler will not be able to handle it for long periods of time.


I seem to have narrowed it down to a new version of Prime95. 26.6 is apparently far less taxing than 28.10.

Can anyone recommend a 360mm radiator which is really silent/has a low amount of vibration? I am allergic to the vibrations the H80i V2 gives off. So I'll need an AIO kit with a pump which is really quiet.

Zka17
Level 16
I am using custom loops, but either way the radiator is not creating the vibrations - the pump, but most likely the fans are doing it (in AIOs the pumps can be a culprit too).
Check some of these kit: https://www.ekwb.com/shop/kits
These are way more efficient than the AIOs, still easy to use.
Pay attention to the radiator size, if it fits your case.

Zka17 wrote:
I am using custom loops, but either way the radiator is not creating the vibrations - the pump, but most likely the fans are doing it (in AIOs the pumps can be a culprit too).
Check some of these kit: https://www.ekwb.com/shop/kits
These are way more efficient than the AIOs, still easy to use.
Pay attention to the radiator size, if it fits your case.


Thank you for the recommendation and link here. I have a very similar system to the OP, although never experienced the overheating issues, and I am using the original H80 cooler. Just lucky I guess, although I don't run stress on the CPU and stick to 4.0 GHz. It appears from the link and researching that site, that you can build a very nice water loop for the CPU (that one) for less than $300 all in, unless I missed something. If only there was a convenient place to mount the pump, lol. Personally I use all 4 drive bays, but thanks again for the link and point in the right direction.

To the OP, if you never plan to stress that CPU you may not need to do anything. As you observed the AIO you have doesn't begin to fail until stressed for a ____ period of time. But I wouldn't be comfortable with those temps either, if you plan to operate in that region.
Davemon50

Godofmosquitoes
Level 7
What about something like the EKWB EK-XLC PREDATOR 360, if I can still get my hands on such a set?