Random shutdowns, GPU defective?

[Taston]

Hi,
For the last few months my PC has been running smoothly with all the latest games but recently has been getting progressively worse, sometimes with graphics glitches, like textures being completely black or white, now to a point where it completely shuts down when I start some of my games up. The weird part is, I have run benchmark tests on it without any problems since the crashes started (3DMark and Heaven).
The problem also occurs after browsing the internet for a while or watching a movie. After the sudden and abrupt shutdown, the PC will only turn on again for a few seconds before again shutting down completely (after about 10 mins it will turn back on as normal). I'm pretty sure the problem isnt overheating, I monitor the temperatures on speedfan and they don't get anywhere near a high level before it shuts down.

Anybody have any ideas where the problem could be?

Specs:
CPU: AMD FX 9590
MOBO: Asus CROSSHAIR V FORMULA-Z 990X
GPU: Zotac GeForce GTX 1070
Hard Drive: Samsung 750 EVO 500GB SSD
PSU: EVGA 850
RAM: HyperX Fury 8GB x4

Thanks!

 

[Iceman21]

I'm suspecting the thermal protection of your psu. Do your psu fan spinning? Try to stop "eco mode" of your psu if you have the option for this.

If you OC-ed something go back to stock speeds.

 

[Taston]

Thanks for the reply, the PSU was not in eco mode, i tried it in both modes but it doesnt make any difference. The fan is spinning at startup, and doesnt feel like its very hot when it shuts down.