So apparently I was using a broken PSU power cable, so I used another one and my brothers system booted up fine with bios and the graphics card spinning. So I put the card into my system, it booted up into windows, but twice the screen turned randomly grey for like a mili second. This is my brand new system and I just didn´t feel comfortable so I shut down my PC and replaced it with the old one. It booted up with a blue screen and I was scared to death, but it restarted, did roubleshooting, restarted again, and sent me to the bios and I booted it up. Everything seems fine now. Maybe it was because I hadn´t installed the drivers beforehand?