Question PC Reboots randomly when under load.

Mar 6, 2021
As the title says, the issue is obvious but the cause isn't so much.
So when gaming, or doing anything graphics intensive everything seems to be working as expected, yet suddenly the PC Shutdowns, and turns back on all by itself. Notably, the second I start Furmark benchmark, the PC reboots IMMEDIATELY. after rendering nearly a single frame, not even that sometimes.

Troubleshooting I've done so far:
1- First suspect, the GPU. So I tested it on a friend's system with Furmark and everything for about 20mins, no reboots whatsoever.
2- Tested the ram, put it in different channels, removed one of the sticks, and ran memtest86 . Didn't make any difference.
3- Tried CPU intensive tasks for quite a while, never reboots.
4- removed all HDDs and only kept the windows SSD, still nothing changed.
5- I tried to replacing GTX 1080 with a 1060, a weaker card, and it still rebooted with Furmark!
6- installed a fresh copy of windows just to eliminate the software side of things.

My System:
CPU: i7-4790k (Stable, not overclocked)
Ram: 16gigs DDR3 HyperX Beast
Mobo: Gigabyte Z97x-SLI
PSU: CoolerMaster G650M (650W)
All I've done has left only 2 variables that are not tested. PSU and Mobo.

I more inclined to believe it's a PSU issue. I assume it only happens when the GPU starts drawing significant amounts of power, however the GTX 1080 maxes out at about 150w, which is nothing compared to the PSU's rated 650w. Also, the 1060 that draws even less than that, still rebooted. So I started to doubt if it's a motherboard issue somehow. And I don't understand if it's a PSU issue, why would it shut down and turn back on, on its own? not just shutdown.
All your help is appreciated, I can't tell for sure if it's a PSU issue and I don't want to buy one in vain.
Last edited:
Mar 6, 2021
By all means it sounds like me too, how old is it? If its faulty it can cause problems even from cpu stress only. Also 4970k is no joke, it has really high peak power draws in rare occasions.
The PSU is about 5 years old at this point. I guess I just wanted another opinion in case I'm missing something. Because when the CPU draws 80w, it doesn't bat an eye. but when the GPU draws that, it's most likely gonna reboot.