Watercooled CPU is getting way too hot

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nick_ta_mere

nick_ta_mere

Commendable
Sep 27, 2016
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1,510
Hi!
This weekend I installed my first custom watercooling loop. Had a bit of trouble with the compression fittings, but otherwise it went a lot smoother than I expected.
Now after a 24h leak test (which showed no leakage) I put in my GPU and connected the PSU to the motherboard and so on and turned it on.
It booted up, but when I check the cpu temps with "openhardware monitor", each core kept jumping between 30C and 50C between a single refresh tick. (While gaming it peaked at 75C)

The pump was running at full speed, the radiator fans were on, the PC was in idle after boot up and the cpu is not yet overclocked.
I check for kinks and couldn't find any.
I have no idea why it got so hot, please help :)

Specs:
CPU: Intel Core i7-4790K, 4x 4.00GHz
MB: Gigabyte GA-Z97X-Gaming GT
CPU Block: Phobya CPU-Cooler UC-2 LT
Radiator: Alphacool NexXxoS ST30 420mm
Pump: Alphacool VPP655
Fans: Corsair CO-9050017-RLED Air Series AF140-LED Quiet Edition 140mm

Things I'm gonna check when I get home from work:
- thermal paste on the cpu block
- the fans were selected for the fancy red LED, maybe they are unsuitable for cooling a rad?
- at the moment only two fans on the radiator, because one was faulty

Pic:
https://postimg.org/image/d6f8vaf17/
 
Solution
rubix_1011
My mistake, I read that incorrectly then.

30C would be pretty average, but maybe a bit high if idle. 30-50C would be pretty normal under nominal to moderate load. 75C would be fairly high for a stock CPU unless you were benching it with Prime or something similar, and even then, I would assume maybe mid 60's C.

Is your pump outlet pushing into your CPU block or the reservoir in the photo? It really shouldn't matter, but preference would be to push coolant to your block. Also, on the pump top, can you confirm the I/O of the ports are correct for inlet/outlet?

What are your ambient room temperatures like? Do your temps stay like that or do they gradually increase over the course of an hour or more?
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infamousk12

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May 2, 2013
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Well, you have selected AF fans for your rad instead of SP fans. For radiators, you want to be using Static Pressure fans (SP), as they are better for pushing air through rad grilles. Corsair sells SP fans with interchangeable rings to match your color coordination in your rig. Personally, I would prioritize performance over aesthetics.
 
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rubix_1011

rubix_1011

Contributing Writer
Moderator
Jan 12, 2007
16,707
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Biggest item here is the overclock.

What voltage are you running the CPU at? What temps do you see at stock speeds and voltages? What temps did you see with the previous cooler at both overclocks and stock speeds?

Core-reported temps are not a direct relation to the actual sustained temps or necessarily an indication of cooling delta. Temperatures will always fluctuate from second to second depending on how much actual load is on the CPU (or GPU). Too much voltage for a specific clock speed can and will cause higher temperatures when overclocked. Have you found the best BIOS settings for the clock speeds you want to sustain, or are you using an automatic overclock setting...or worse, a GUI overclocking tool?
 
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rubix_1011

rubix_1011

Contributing Writer
Moderator
Jan 12, 2007
16,707
660
60,190
My mistake, I read that incorrectly then.

30C would be pretty average, but maybe a bit high if idle. 30-50C would be pretty normal under nominal to moderate load. 75C would be fairly high for a stock CPU unless you were benching it with Prime or something similar, and even then, I would assume maybe mid 60's C.

Is your pump outlet pushing into your CPU block or the reservoir in the photo? It really shouldn't matter, but preference would be to push coolant to your block. Also, on the pump top, can you confirm the I/O of the ports are correct for inlet/outlet?

What are your ambient room temperatures like? Do your temps stay like that or do they gradually increase over the course of an hour or more?
 
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Solution
CountMike

CountMike

Titan
Oct 31, 2015
33,782
3,151
147,990
Can't expect water or any large cooler to keep idle temps less than 5 -10c above ambient temps. Only at heavy loads they would work better than smaller ones, air or liquid. So temps under light load or at idle are not representative of cooling capacity.
 
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nick_ta_mere

nick_ta_mere

Commendable
Sep 27, 2016
3
0
1,510
Ambient temp is ~22C, so up to 50C during idle can't be right. (and 75C under load, which would have risen higher if I hadn't cancelled the test)
My setup is: reservoir->pump->cpu->radiator->reservoir
inlets and outlets are marked on the pump, so I'm sure I connected it correctly. I'm not entirely sure of the pump's orientation, since there is not mention of that in the manual.
 
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