Some random French guy here, I have since June 2015 the following computer :

  • CPU Quad-Core Intel Core i7 4th Gen (Intel Core i7-4790K (4.0 GHz / 4.4 GHz Turbo - Cache 8 Mo)
  • Motherboard Gigabyte GA-Z97X-Gaming 3 (Intel Z97 Express)
  • 16 Go RAM DDR3 1600 MHz
  • NVIDIA GeForce GTX 970 4Go
  • SSD 240 Go Serial ATA 6Gb/s
  • HDD Seagate Barracuda 7200.14 SATA 6Gb/s 1 To
  • NZXT Phantom Case
  • PSU 650W LDLC QS-650+ Quality Select 80PLUS Gold
  • Fan for CPU Noctua NH-U12P SE2

(If needed, bought from this website, but it's in French > https://www.ldlc.com/fiche/PB00100625.html)

No problem back then, this PC is quite powerful and all, but since some weeks, it restarts when gaming, like a security overheating or else.

I've made multiple tests, and here what I've found so far:

  • CPU is always under 50°C, even under 40°C most of the time, during gaming too.
  • GPU is increasing to 80° pretty quickly (less than 1mn), and cannot go over since the computer force a shutdown.
  • I don't see any anomaly with the fans, I've boosted them to full speed, and can see/hear the difference
  • I've made a full clean up of the hardware, even dismounted PSU to clean everything.

While I first thought it could be the GPU, I don't really think so, because I've ran FurMark to benchmark the GPU like hell, up to 83°C for several minutes, and nothing happened, computer was fine, no shutdown or reboot for overheating. And when I was playing (Elite Dangerous mainly, no problem for 2 years), when GPU was going over 80°C, PC would shutdown, but yesterday, during game loading, GPU was around 65°C, and it crashed too.

So now I think it could be a PSU problem, but from that, I don't really know how to check (I have a multimeter, but I'm not an elec guy, just a developer).

Also, even if I don't think it, maybe it's a software problem, I've formatted my computer yesterday evening, I'll do some new tests this evening (UTC+01).

Also, I've ordered some thermal paste, dunno if my GPU has by default, even though, I'll check that and replace/add it, cannot be worse with it (I should just change to a 1080Ti, meh).

Dunno what more I could do, I'm here to seek your help! =)

  • I would guess PSU as well based on what you've ruled out so far. You might try running FurMark at the same time as a CPU test like Prime95 to see if the increased draw of GPU and CPU simultaneously causes the shutdown. If you have a way to track wattage from your wall mains (like a Kill-a-watt), you could see if it only occurs above a certain wattage. – techturtle Oct 30 '17 at 14:13

Well, problem has been solved, so here were my problems:

  • PSU was indeed failing, but after getting a new one from my supplier, computer now couldn't even boot.
  • So the other problem was RAM, one of them was completely dead. Removed it and since computer works like a charm.

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