[SOLVED] Watercooled system black screens after maintenance ?

[Koykis]

Hello everyone,

I've got a problem with my main system.

Specs:
MOBO: Asus Prime X470
CPU: Ryzen 3700X
RAM: 16GB Gskill SniperX
GPU: MSI 1080 Ti Sea Hawk EK
PSU: Corsair RM750
COOLING: Alphacool 360 Kit

Issue:
After routine maintenance of water cooling loop (flush, fittings check, refill) the PC stopped outputting video. Once in a while it will go past BIOS and boot to the OS, black screen 1-2 minutes later with everything else SEEMINGLY working normally. In subsequent restarts the system seems to boot normally but the screen does not get a signal (connected through HDMI).

Details:
This started happening when I did a routine maintenance to the cooling loop as mentioned above. The system booted normally to Windows where I routinely run 15-20 minutes of Unigine Heaven with HWmonitor open just to see that everything runs normally. The GPU temps started normalizing @ 60-65C after a few minutes, depending on the scene, and the CPU sits @ ~40C, so since everything seemed normal I went to the kitchen to grab an apple. When I returned to my office room the computer was still running but the screen had gone black. I guessed there was a crash or something so I hit the reset button and waited for the BIOS splash to appear, which never did. The keyboard was working and it felt like the computer had booted to the main OS (Linux) 'cause when I spammed Ctrl+Alt+Del it rebooted. Since then, once in every few hours I get it to reach the OS for a couple of minutes until it crashes to a black screen again.

First thing I check (when and if I manage to get to the OS) is temperatures. GPU is sitting idle @25-30C and CPU idle @ ~35C. I tried taking the GPU apart, repaste, check all the pads, refit the block and check again with no change. I also tried swapping the PCIe cable slots on the PSU to check if one of the rails was not giving enough power, still with no change. I would like to hear your guy's thoughts since I hate to think like that but I have a feeling the GPU is fried. I got it used a few months back and it had been working fine, if not a little bit warm, but I never thought a high-end GPU like that would get damaged by temps lower than 80C, even if it was used for mining or whatever. I don't think it was though, do miners get such expensive models to spend money on open cooling loops?

Anyway, that would be all. Sorry for the long post, if we get it fixed I promise I will share e-beers with everyone xD

Cheers!

 

[Eximo]

I hate to say it, but try taking the GPU out and putting it back in the slot...

My guess would be you jostled something during your maintenance, all it takes is one little pin to be slightly intermittent and you can get all sorts of problems. It would make some sense as well, probably works cold, then as it warms up, loses connection.

 

[Koykis]

Thank you for the quick response @Eximo!

The whole re-fitting, re-pasting etc. was done after the initial maintenance and I noticed the problem. But you gave me an idea, I'll try re-routing the PCIe power cables from the top of the card 'cause with all the fiddling with the watercooling I had been yanking them a lot and might have displaced something...

I'll come back with results.

 

[Koykis]

Never mind... I'm just careless I suppose. I had a very slight leak at my GPU's block inlet and noticed it only after leaving the system off for a while and the coolant just sat and made a little puddle around the fitting.

Anyway, temps are stable and the system runs fine. I guess I need to name it now to prevent such "unlucky" (dumb in truth) incidents to happen again. But most of all, I want to thank @Eximo and everyone here that would surely lend a hand to resolve the issue. Now that I have an account I will take the opportunity to try and help other members. Can I mark this as resolved or should a mod do it?

Cheers!