PC black screen and 100% fans while gaming (Not overheating)

[klokklok]

Hello everyone!

For some reason my pc started crashing when starting up a game since yesterday. The screen turns black and my fans go 100%.

I decided to check if my pc overheated but it didn't. My CPU and GPU temps didn't go above 60°C and usually stayed around 50°C.

PC Specs:
HDD: Seagate Barracuda 7200.14 - 1TB
SSD: Samsung SSD 840 EVO 250GB
CPU: Intel Core I7 6700k
GPU: Gigabyte GeForce GTX 1070 G1 Gaming
MOBO: MSI Z170A GAMING PRO CARBON
PSU: XFX XTR Series - 650W
OS: Windows 10 64 bit

When I start up a game my pc crashes at random times. Sometimes while loading but other times after like 30 min.

Does anyone here have an idea what causes this problem?

 

[klokklok]

After some restarts I got a warning that my GPU power cable wasn't attached anymore. I think it slowly disconnected from the graphics card. I pushed it back and now my problem is solved.