[SOLVED] CPU 100°C - AiO Radiator does not get hot

[shallowClone]

Hi guys,
so today I noticed that my CPU jumps to 100°C sometimes when playing games.

Setup:
ROG STRIX Z370-G GAMING
GSkill F4-3200C16-8GTZR x2
Intel(R) Core(TM) i7-8700K CPU
Deepcool Captain 240EX AIO

The radiator is in the front with two 120mm fans pulling air through the front. To fans on top and one on the back pull air outside.

Idle temps are 34°C

I changed the heat paste already but no changes. Also, I tried to run the pump at 100% all the time also no changes.

The radiator stays cool and can be easily touched. I can feel water get pumped through the pipes to the radiator.

If CPU temp hits 100°C while gaming the POST State LED for CPU lights.

Temperatures are taken with the lm-sensors package on Arch Linux.

I'm out of ideas what could be wrong. Pump broken? Air bubble?

Best regards,
Max

 

[rubix_1011]

Sounds like the base plate isn't seated very well on your CPU - just enough for idle to be sustained, but as long as idle temps remain the same and do not increase more than 1-2C, then I would say the pump is working.

If your idle temps over the course of several minutes slowly climb higher and higher without launching any software, I would then say the pump is not actually pushing coolant, likely due to an airlock. Pump may be running, but not pushing coolant. Wiggle (gently) the tubing lines and even tap the pump and radiator.

No AIO should ever be too hot to touch - that isn't how the temps being reported work. These are on-die temps of your CPU. They are not an indication of the coolant temperature.

 

[shallowClone]

The temperature in idle and even under normal load are almost the same with like a maximum of 40°C. Even after letting it run for hours like that.
So the problem is most likely the mounting problem you mentioned? I tightened everything down when I switched the heat paste but if that's the most likely thing I will tear everything out again and remount it afterward.

The thing is even if the CPU hits 100°C I can easily touch the pump block. and everything feels quite cool even around the motherboard there.

Thanks for the help!

 

[rubix_1011]

I am assuming you do not have the CPU overclocked, correct?

If you run some sort of load on the CPU, how quickly does it reach 100C? Is it nearly immediate, or does it take some time?

When you pulled the CPU block off, was there an even spread of thermal compound on the IHS of the CPU, or did it look offset on one side? And when you re-apply the CPU block/pump, you are fully tightening everything down, correct? And there isn't any thread slack between the standoffs and the backplate, right? (this would prevent you from fully seating the pump, but would seem it is fully torqued down)

Funny thing you mention this cooler...I'm doing testing and review of a newer version of this cooler right now.

Either way, something doesn't add up.

 

[shallowClone]

Exactly no overclock because I was really satisfied anyway with the performance.
It's really fast like 3-4 seconds I would say.
Was evenly spread yes. I will check for the slack that's something I haven't checked yet and that could be the reason.

It did run excellent for like 1-2 years now this is the first time that I have issues.

Yes, I will check everything tomorrow and tell you how it did go. Thank you for your fast responses so far! I'm really appreciating it.

 

[shallowClone]

So I completely ripped out everything and rebuilt it the system seems cooler right now.
With CPU-Z stress test Temp rises to 82°C but my ambient is quite high.
I checked the Intel Temperature Guide but I'm not sure if everything is fine as my TDP is 95.0W but with the test the power rises to 107.5W in Core Temp.
And thank you for the tip with the slack I'm sure that has been the problem!