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Not able to cool i9-9900K with a 360mm CUSTOM LOOP!!!


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I own an i9-9900K and I bought a 360mm radiator with a custom loop ONLY FOR THE CPU (EK Fluid gaming A360G) to cool it.
But I have really high temps at stock clocks: When runing Aida 64 engineer FPU stress for 10 minutes, it throttles in a 8-14%range. With tems really high. CPU at: 83º, CPU core 1: 90ª, CPU c2: 75ª, core 3: 98ª cpu cre 4: 
100ª e.t.c 

I think these tems are really high for a custom 360mm loop. What do you think? What could be causing the issue???

IMAGE OF MY LOOP: https://drive.google.com/file/d/1cNs76kNV0j9YuIJhHNNSVgu-tbtrE_KX/view

The "hot" air comming out from the radiator is not hot, and the liquid temp. comparison between the inlet "cool fluid" and the outlet "hot fluid" is of only 1,2º.



-idle tems are of 23º (CPU general) and between 30-32º in core 1,2 e.t.c.

-Temps (After benchmark) drop dramatically back down to idle temps .

-The pump is moving coolant. Punp PWM is being used and the pump (when tems are above 60º) is at full speed.

-The thermal compound is the one provided by EK.

-CPU temp jumps (when running Aida64 stressing cpu, FPU and cache) very quickly to high temps in about 1-2 seconds.

-The total package power under load (when running Aida64 stressing cpu, FPU and cache) is of 188W aprox.

-Case: Cooler master mastercase H500M



I do need help with this.



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80-90C is not unusual for the i9-9900K during stress testing.  Note that the default thermal throttling temperature is 100C for this CPU, however, most OC guides that I've read suggest upping this threshold to 110C in the BIOS.  Then you should never see throtting within AIDA64 stress testing.

It is not clear to me, from your picture, where you are drawing air into the radiator from.  If you can, then the best CPU cooling will be achieved drawing air from outside through a radiator at the front of the case and then exhausting out of the top.  You can use PMW case fans to cool the other components.

I cool my i9-9900K with a Corsair H115i AIO in a push-pull config at the front of my case.  I can run AIDA64 stress testing all day long overclocked to 5.1GHz / PC3400 without ever seeing any thermal throttling.

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I have the same waterblock and a 360 rad cooling the CPU, northbridge, VRM's and a RTX2080 with no problems. The fact that your temperature shoots right up would suggest that the cpu isn't transmitting the heat to your block. If it were then your outgoing fluid should be warm to the touch if its running that hot.

A few things I can think of are:

1) You forgot to remove the clear plastic cover from the new waterblocks copper surface. (don't laugh I've done it)

2) Not enough thermal paste or the block isn't tightened down enough

3) Wrong restrictor plate installed on waterblock (even then tho I wouldn't think it would get that hot)

4) The CPU needs to be lapped, you could check how flat the top of it is with a straight edge.

Is it a new cpu or a new waterblock?

Is the waterblock itself getting hot? (and the fluid inside it)

Can you see the fluid moving?

Is the reservoir warm to the touch?

Make sure the CPU is making good contact with the waterblock. Sounds like that may be where your problem is.


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  • 4 months later...


I apologise for the time I took on answering you.

I finally managed to cool properly the loop. My problems were the following:

-Lots of air bubbles in the loop

-Extreme Vcore voltage

-Not enough imput air to the radiator


Now I can run it at 5Ghz without throddling.



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