Build Advice Overheating CPU on Custom Built PC

May 8, 2019

So I obtained a custom built PC, I personally have very, very limited knowledge about custom builds or PCs in general. I had been using it for months maybe even a year with no problems. Then a couple of weeks ago it froze, I could only do anything by using the reset button on the front panel. I restarted, logged in, continued to use thinking it was a one off. Ended up happening about 3 times in one day. I tried updating windows and drivers to no avail. There was no system restore point from before the issue so I reinstalled windows. Again this made no difference. So to cut out a long back and forth, essentially I have tidied up the inside of the case from the previous owner, repositioned the water cooling fans and radiator to the front panel rather than the top and made a few fan placement chamges for better airflow. Now the odd thing is, nothing I have tried has made a difference to the freezing / overheating. That is, until I reapplied thermal paste to the CPU /water cooler contact. For the first evening of use the CPU temp was around 45° whilst playing Assasins Creed Odyssey with full graphics settings on a 1080 monitor. The second day the cpu temp was around 60° and by the third was freezing again - even just sitting on the desktop with nothing running the idle temp was around 70°. I have repeated this about 3 times with the same results. On night 1, the CPU and cooler temps are within 6° of each other. By night 3 there is a difference of 20°.

I have tried various fan placement, speeds and settings. However, surely if the temps are all perfectly healthy on night 1 and then skyrocketting by jight 3 this is indication that fan placement isn't the issue?

My knowledge of these matters is fairly well presented in this post. I am at the boundaries of my expertise.

Other information that might help;
• The GPU temp seems to be fairly normal. About 60-70° whilst playing AC. Sometimes lower.
• The motherboard shows 3 temps on Corsair link - I don't know exactly what they are refering to. Those temps are very high when the CPU temp is high and normal when CPU is normal. I don't know the cause and effect relationship between them.
• When I have taken off the water cooling 'thing' from the CPU, the metal bracket that you screw the cooling 'thing' to is somehwat loose. It is all solid when screwed on though.
• I have tried disabling the CPU turbo feature in BIOS but not changed anything else as I don't know what I'm doing. It made no difference anyhow.
• About 2 weeks prior to this issue I installed a UAD soundcard in the PCIe slot. But was using PC extensively between this installation and issues with no problems at all.
• The third time I reapplied thermal paste I removed the actual CPU from it's housing. I noticed a small amount of the black rubber between the metal plate and the circuit board was inside the gap rather than looking like a connection as in other areas. There were small amounts of thermal paste in these areas which I tried to clean away - I guessed that thermal paste sitting on the CPU wpuld be holding heat onto the CPU. Couldn't fully remove every last molecule of residue though.

In conclusion it seems that the reapplication of thermal paste works in cooling adequately for the first boot and usage before turning off / or a set amount of time. I haven't tried leaving it on continuously after reapplication for fear of overheating and damage when I'm not there. I have been monitoring temps whilst playing AC on a second monitor showing Corsair LINK.

Motherboard - GA-990FX-GAMING
CPU - AMD FX-9590
Cooler - Corsair H100i V2
Windows 10.

After writing this I found I had actually left it on accidentally for a couple of hours. All exernals were nit working. No lights on keyboard or mouse. Monitors not receiving signal. Reset button on front panel non resposive. Power button none responsive. Internal lighting still on. Fans on. No external operation.
May also be worth noting that during the normal freeze all externals turn off then on again but are totally unresponsive.
I had to just use thd main power switch to kill it. Turned it on, got to login and all externals went off. Booted up to BIOS - CPU temp at 79°.

Thanks in advance for any help. You computer people are great, for every moron making a virus there's a hundred of you offering free help.


Edit- On boot up I very briefly see "MB ERROR 3'
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Can you feel if the pump is moving when everything's on? If your liquid cooler isn't pumping, then there's no heat transfer, which explains your high temperatures.

This may be a long diagnosis, so be patient. Unfortunately, the 9370/9590 are real messes that probably should never have been released to the consumer market.


The 9 series FX cpus were/are a disaster AMD would love to forget ever happened. When first released, they came with an AIO that was equivalent to an H80i. That lasted less than a year because ebay sales of those coolers went through the roof. Everybody with half a brain didn't even bother unboxing the cooler. It's not that it was junk, just totally inadequate for anything other than websurfing loads. The Corsair H100i is a realistic absolute minimum cooler, even the Noctua NH-D15 can barely keep those cpus cool on reduced stock settings, nevermind the 5.0-5.2GHz those cpus are rated for.

So just how old is that H100i? If it's anywhere close to @ 5years old, it's done. With those temps and that usage, you'll see exaggerated coolant loss through evaporation from the tubing and possibly coolant breakdown.

There's only 1 recommended cooling solution for the 9 series FX, full custom loop. What's bad, is that now costs more than the pc is worth, so buying a loop is just throwing good money after bad.

The cheapest solution is dump the FX9 and replace it with a FX8350/8370, a decent cooler and OC the cpu back up to @ 4.8-5.0GHz. Half the wattage output for the same performance. A Lot less worry on thermals.

Best solution would be a platform change. For $400 or less, a R5 1600/2600, 16Gb 3000/3200 DDR4 on a B450 mobo, keep everthing else. Better performance, even with OC on the stock Wraith cooler and considerably lower thermals. Pc will run faster, smoother and quieter.