PC wont start with new GPU

[Myth1337]

I just bought a new GPU (XFX R9 390 Black) and a second RAM kit (G.Skill RipjawsX F3-14900CL9D-8GBXL). At first the pc wouldn't boot into bios or windows with all 4 ram sticks and the 390 installed so I assumed the problem was with the ram and took the 2 new sticks out. The pc booted. I proceeded to install new drivers for the 390 and did a benchmark in tomb raider. Everything worked fine, I got 160fps avg I think. I then went on google to troubleshoot the RAM problem I tought I have and the pc turned off mid browsing and wouldn't turn on again. After testing the PSU on a second pc, resetting bios cmos and swapping the rams in all possible ways I finally took out the 390 and now the pc works with all 4 ram sticks and the old 7870GHZ gpu. I have tried resetting BIOS to default settings but to no avail. Do I have a busted gpu or have I overlooked something?

My Specs:
MB: Gigabyte GA-Z97P-D3
PSU: LC6650GP2 V2.3 650W
RAM: G.Skill RipjawsX F3-14900CL9D-8GBXL x2
CPU: i5-4690k@4.5ghz (cooled with Thermalright Macho Rev.A 120)
SSD: Crucial MX100 256GB
HDD: WD6400AAKS 640GB

 

[Tmagic650]

Any luck with this?