7900X 100C at Load

Moondoom

Moondoom

Moondoom

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12 Nov 2017
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5
Hi guys, it seems that I have some really strange issue with my CPU temp.

Long story in short:
Mobo: Asus R6E, bios: 1002
CPU: 7900X - non delided - Water block (EK CPU+VRM combo unit)
GPU: Strix 1080 TI - Water block (EK Block)
Cooling loop: Full custom loop, 360PE(45mm) + 360SE(30mm) + EK 140 Res + D5 Pump combo (glass) + 6 EK Vadar fans 2200Rpm
Case: Be Quiet! Darkbase Pro 900

My temps are all fine, except the CPU. But the CPU is horrible: Under load at Stock(!) the temp goes up to 70°C-75°C.

If I overclock it a bit to 4.5 Ghz, at 1.15V (Stable, no issues and still under the recommended 1.2V) CPU package temp goes up to 100-102°C under Cinebench.

Additional info:
Room temp around 23°C, Water temp at idle 31°C - 38°C under heavy load, GPU at 32°C idle - 45°C in gaming, VRM at 36°C idle - 65°C under heavy load. Pump is always on 100%. Fan speeds are irrelevant since the water temp never exceeds 38°C. CPU 35-38°C idle - load temps...100°C or higher...

I know that the Skylake-X CPUs are hot, but I have never seen temps like these for the CPU under this low voltage.

I have tried the following things:
Reseat the CPU block.
Re-apply thermal paste.

Do you have any suggestions what can cause these temps?
 
If water temps are fine, then it has to be a bad mount, or an issue with the water block.

Does the CPU waterblock have an in and out? Are they the right way round?

Is the block making good contact with the heatspreader? Maybe try a washer to get more clamping force if its safe to do so and see if that helps?

And, I have to ask, if it was new, are you 100% sure there was no protective film on the bottom of the block that you forgot to remove?

EDIT - wow, 10 core 20 thread? You sure thats not just normal for a chip like that?
 
Last edited:
Does the CPU waterblock have an in and out? Are they the right way round?
Click to expand...
Yes, the WB has an in and outlet, all connected correctly.
Is the block making good contact with the heatspreader?
Click to expand...
Yes, all good, the thermal paste spread equally.
And, I have to ask, if it was new, are you 100% sure there was no protective film on the bottom of the block that you forgot to remove?
Click to expand...
There was, but I have removed it before the first use.
 
That seems very high, as mine was running at 4.6/4.7 @ 1.180 / 1.200 running 80/90's, what are you using to test the load? Is it just Cinebench R15 or are you using Prime 95 etc... ? The water temps look a little on the high side for my personal preferences.

What are you OC setting other than the vCore?
 
Ok, found out some things myself. For some reason if I use adaptive voltage, the 1.16 base, -0.001 I still get 1.22-1.24 (according to HWInfo). Temps go up to 103°C, 2 cores are throttling. However if I set the voltage to 1.16 Manual, it runs "only" at 93°C. The system is stable at 4.6 - 1.16 Volts. After I set the voltages manually, most of my issues seems to be gone.
 
1.22 - 1.24 on the vCore will cause things to get toasty on a no delidded CPU, so I would expect those readings which you have stated above. As a rule of thumb most 7900X's will do at 1.200 vCore, so that would be a good starting ground to find your max stable OC, Mesh multiplier can also have a big bearing on the heat output and can cause system instability. Generally 30 seems a safe bet on most high overclocks but pushing that to 32 often doesn't net any noticeable increases but may need a cache voltage bump as well which would mean more heat.

Have you testing the board at stock with the Asus MCE disabled to see what your temps look like? Also what Thermal paste are you using?
 
I am thinking you would benefit massively from delidding the chip. Get some liquid metal under there and temps should drop loads.

Also you could get a 12 core instead as they run much cooler due to having a much bigger die shared with the 18 core.
 
I do want to delid the CPU, but I have never done it on any of my other CPUs, so I'm afraid that I would damage the unit itself. Also, it seems like ocuk is out of the delider this time.
 
Moondoom said:
I do want to delid the CPU, but I have never done it on any of my other CPUs, so I'm afraid that I would damage the unit itself. Also, it seems like ocuk is out of the delider this time.
Click to expand...

It's pretty straight forward, just take you time but with all these things there is a risk. This was my first delid and I used the Rockit 99 delid kit, if you search you YouTube there are a number of good how to's on it.
 
Jumper118 said:
I am thinking you would benefit massively from delidding the chip. Get some liquid metal under there and temps should drop loads.

Also you could get a 12 core instead as they run much cooler due to having a much bigger die shared with the 18 core.
Click to expand...

Yup this is basically it. As processes get smaller and smaller you end up with more cores crowded and dumping more heat in a smaller area. This along with Intels crap TIM mean you simply can’t get the heat away quick enough without a delid, even on water.
 
Delid it and also the SE360 is a complete potato and by far the worst pairing with that setup. Better thicker low FPI rad and improved air flow.
 
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