Pc restarts with monitor going black

[Nullflare]

Hey guys. In the past couple days my pc has been restarting and the monitor going black. I've seen a few threads already, ranging from. Gfx card to psu to flonky cables etc. So figured I'd post my specs to see if I or anyone else could help with the problem.

Like I said, only started in the past couple days.

Mobo - ASUS M5A78L‑M/USB3
Ram - 8gb ddr3
Gfx card -nvidia gtx 970
Cpu - amd fx-8120
Psu - corsair 650w

That's the gist of it. The pc is a couple years old, the gfx card was new in January. Have a new case and a new cooler for my psu coming.

I do think think it's the gfx card because I have an old gtx 650 mini that I bought with the pc and have plugged it in and it's still restarting.

Could be overheating of the gfx cards/psu, they run around 78c when I'm playing games, max temp according hw monitor.

Any info or insights would be greatly appreciated. If you need any more info, let me know.

Edit: since posting, my pc turns on but the monitor doesn't work at all. I have 2 cables and 2 monitors and when I try my pc with either nothing comes on. The pc powers up, can hear the fans come on and everything but both monitors stay in sleep mode with orange lights. One of them is a little more up to date and says there is no input through either vga cable

 

[Lutfij]

1| You forgot to include the OS to your system and the model of your Corsair PSU since Corsair make a wide range of units in a number of series's.
2| The sign of a reboot under strenuous activity is a sign that your PSU is failing. Just to be sure try and go into your BIOS and see if the ram is being reported as it should with the right voltage, timings and frequency.
3| It's a good idea to take the presumed faulty GPU's and test them at your friends place provided he has more than enough power to run said cards.
4| Can you get into BIOS at all?