Weird problem with my PC, totally stuck, what next?

AdvocateUK

Commendable
Feb 21, 2016
3
0
1,510
Hi all,

I recently built a PC (6 months ago...ish) from the following parts

MSI Z77-GD55A Mobo - bought from my son used
Intel i5 3570k CPU - bought from my son used
16GB memory bought used from my son
16GB memory bought new
EVGA GTX970 GPU bought new
EVGA PSU (can't remember how many watts but it was fairly high)
Pioneer Blu-Ray writer bought new
Samsung 850 250GB SSD bought new
2 x 500GB HD's that I've had lying around for a while, after they had been in my Mac Pro
NZXT Case

From initially being built it would sometimes not boot when switched on, all I'd get is a black screen it wouldn't even POST, but if I switched it off and back on again it would boot fine. So I didn't think too much of it. Witcher 3 came with the GPU but whenever I tried to play it it crashed the computer and I had to reboot. Again, I didn't think too much of it as I wasn't really that bothered about playing that game.

Well, the computer has sat there not used much due to work commitments until yesterday when I tried playing Witcher 3 again. As usual the PC crashed except this time it wouldn't boot, I tried everything, checked every component was seated correctly, tried a different GPU, tried the built-in GPU, tried with no HDD, tried with a different HDD. In the end I figured it was the motherboard and/or the CPU and settled myself on the fact that I'd have to buy a new one of each.

At the time my other half was out, and when she came in I was sitting on the floor with the PC in bits and I told her the bad news, that we were probably going to be £400 or so out of pocket to replace the bits that needed replacing. As I was telling her this I pulled the power socket out of the mob and put it back in again, lo and behold the PC came on, got through POST and booted! I couldn't believe it. I switched it off and back on numerous times, and each time it booted fine. Then I did something a bit silly, I started up Witcher 3 again. As I expected it eventually crashed the PC and it refused to switch on again.

After some length of time the PC eventually switched on, I left it on last night running Memtest, which it passed fine.

Some points to note.
When the Witcher 3 crashes the screen goes black but the sounds continue to play, if I press ctrl-alt-delete the sounds stop so I'm guessing the PC is still responding to key presses.
Cities Skylines also crashes like this, but I haven't tested to see if the PC breaks in the same way yet.
Nothing is overclocked in any way, and I have reset the BIOS back to defaults.

My next steps, when I get time, is to maybe try Linux and see if Steam games (Cities Skylines) crash in the same way, to rule out Windows 10 as the culprit. To take the motherboard out of the case and run it caseless, to rule out something shorting out, though I doubt it's a short as the crashes are the same each time and I'd have thought that something shorting out would be random in nature. I'll re-flash the BIOS as well to rule that out.

So I'm stuck for ideas as to what could be wrong, and am turning to the collective intelligence of the ars forums for help. Short of some exotic BIOS virus what could be wrong with my PC? Is it fixable? Do I just accept that it's possessed and replace the mobo/CPU?

In all my years of building PC's I've never had a problem like this, or been as totally clueless about what might be causing a problem. I really am stumped. I don't want to spend £400-£600 replacing the mobo/CPU without knowing the cause of the problems in case it happens again, leaving me even more out of pocket.

If you've got this far then thank you for taking the time to read my long post, I sincerely hope you can help :)
 
Solution
If it keeps on working as is should you not worry too much,just enjoy it. ;)

For the streaming service issues could you try to remove current drivers with DDU in safe mode and reinstall the latest WHQL drivers from nvidia,see if that fixes those problems.

Vic 40

Titan
Ambassador
Since under load you might want to check the psu.If you can test with another one. Would be nice to know which model and wattage.

Mixing ram can also give issues.Try with the set you already had and see if this is good.Test also with the new set.I'm going to assume the motherboard has the XMP feature in the bios,set it to enabled for best ram settings. Might first want to reset the bios to optimal default values,after that enable XMP.

You can see at what speed the ram works with cpu-z (freeware) in the memory tab,in the spd tab are the values it should be able to work at.
 

AdvocateUK

Commendable
Feb 21, 2016
3
0
1,510
That should have read re-flashing, not refreshing, damn autocorrect.

Anyway, the PC continues to boot perfectly every time, and the Witcher 3 crashes turned out to be caused by the nVidia streaming service. Once I stopped that process the game stopped crashing.

I'm still at a total loss as to the cause of my woes though, and not entirely sure that I trust this PC anymore.
 

Vic 40

Titan
Ambassador
If it keeps on working as is should you not worry too much,just enjoy it. ;)

For the streaming service issues could you try to remove current drivers with DDU in safe mode and reinstall the latest WHQL drivers from nvidia,see if that fixes those problems.
 
Solution