Question Ryzen 5 2600 with liquid cooling overheating

Jul 16, 2022
Hi all,

I've got an issue with a gaming pc overheating and shutting down. The setup is:
  • Asus B450M-A motherboards
  • Ryzen 5 2600 processor
  • Deepcool Smarter case
  • Silverstone PF120 AIO cooler (can't fit a radiator larger than 120mm)
  • Gigabyte Aorus RX580 GPU
We have 2 other PCs running the same motherboard and CPU. One has the same case and AIO cooler, the other has a slightly larger case and a 240 AIO. Neither of these are displaying any issues - CPU temps tend to stay under 60 degrees C.

Both PCs in the Deepcool cases have a 120mm fan on the radiator at the back and another 120mm fan at the front.

All of the AIO coolers are mounted to minimise the risk of bubbles anywhere other than the top of the radiator, with the hose connections at the bottom of the radiator and the pump lower than the top of the radiator.

None of these PCs have been overclocked in any way. I personally built all 3 of these PCs (and may others over the years) and no-one else has worked on them, so I know the settings haven't been altered. (CPU voltages on Auto and hover between 0.8 and 1.25V depending on load).

The PC that is overheating can sometimes run fine, for example yesterday it was used for playing games (Roblox and similar) and discord for a number of hours with CPUID HWMonitor showing it was running hotter than it should (CPU occasionally over 70 degrees C), however a couple of times in recent weeks it has just shut down and then gave a Bios CPU Overheat warning when starting up again. This morning we were going to some testing to try to isolate the problem and after around 10-15 minutes of running mostly at the desktop it shut down again. During this time I had the side of the case off and was checking the AIO cooler - there were no unusual sounds (gurgling, etc). HWmonitor gave a pump speed of around 3000 - 3500 RPM. After the PC shut itself down the pump housing felt warm but not hot to touch, and one hose felt slightly warmer than the other so the pump and radiator seem to be working and nothing felt like it was anywhere near 100 degrees C. The case and cooling system is relatively free of dust.

I then pulled the pump off the CPU, cleaned it all up, reapplied thermal paste and reinstalled the pump. On restart we opened up HWMonitor as soon as the PC booted into windows and it was immediately reading a CPU temp of 63 degrees C. Within a couple of minutes this climbed to high 90s - all we were doing in this time was installing the AMD Ryzen Master program to double check some things, so nothing at all strenuous for the computer. When the CPU reached the high 90s we shut it down before it shut itself down.

I was thinking this was a cooler issue, however now I'm not so sure. Other than it getting hotter than it should and occasionally overheating to the point of shut down, the PC seems to run normally (no lagging that might be due to thermal throttling or anything like that).

Where would this issue likely be? The AIO cooler? Or the CPU itself?

Thanks for any assistance.


A)Cooler has accumulated sediment/gunk over time, or the fluid in that unit is contaminated. Check tubing while under a load - Cinebench R23 or Cpu-Z stress test.
Ultimately nothing you can do about this one; these units aren't user-serviceable, so it will need to be replaced. If it's within warranty, do that.

B)A rare occurrence, but a poor cpu solder job. If you still have the Wraith cooler or something else lying around, use that... or simply switch one of the other AIOs in there temporarily and see if thermals still climb to the max.

C)Bad batch of thermal paste. Hmm, not likely, since the other PCs should exhibit the same issue if you used it on them.

one hose felt slightly warmer than the other so the pump and radiator seem to be working
That step should be done with the cpu under load(for at least a couple minutes to allow time to soak), such as Cinebench R23 or Cpu-Z stress test. You're not really putting any power through the loop if the system just sits on the desktop.
Though if it shuts down before you can get a chance to really check that, then that's method's no good.
Jul 16, 2022
Update: I just swapped the cpus between the overheating pc and one of the others. The same PC with a different CPU is still getting up to high 90 degrees C within a few minutes of booting up and without running too much (we only opened HWMonitor, Ryzen Master and Firefox). 2 or 3 minutes after shutting down, the AIO pump casing was quite warm to touch, however the hoses and radiator felt quite cold.

The other PC which now contains the previously suspect CPU is still running at a normal temperature, low to mid 30 degrees C when idling at Windows desktop.

After changing the CPUs and checking temps, I also just tried plugging the AIO into a HDD power plug and the radiator fan into the CPU_Fan header. This PC is now running cooler, but still in the 50s when idling and hovering around 80 degrees C with some load (Firefox and Roblox).

The third PC which has the same case and AIO runs around 50 degrees C when playing a more intensive game like ESO.

So, I think there must be something wrong with the AIO cooler.

Edit to add - Thanks to Phaaze for the reply. I can confirm the same thermal paste was used on all 3 PCs, and swapping CPUs hasn't changed anything so that rules out B and C. The suspect AIO cooler was purchased in Feb 2021 and apparently had a 3 year warranty so that may be an option. I'll pursue that.

Edit (again) - while I was writing this update, the overheating PC's CPU temp crept from 80 up to 95 while under continuous minor load so a stress-test is not going to be possible as it will probably overheat and shutdown very quickly.
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and one hose felt slightly warmer than the other so the pump and radiator seem to be working
Not correct. With a pump and rad on working order, there's only a 1-2°C difference between input and output hoses, not enough for really anyone to physically tell the difference.

My guess is you have gunk build up on the microfins of the pump. With shutdowns, if the gunk is small enough, it can dislodge and pass through the pump on restart, only to get caught up again on the return trip around. This has the affect of blocking flow to a certain extent, and with flow blocked, the coolant at the pump climbs in temp.

With a total blockage, the cpu overheats, with a partial blockage the coolant barely moves but is enough to move the overheated coolant up the outlet, which then heats up the tube.