Here's the story.. I got a p8z77 vlk mobo, 8gb ram, 500evga Psu and I have 700 psu as well, gtx 960 i5 2500k.. I bought a r9 390, i hooked it up with the 700 psu.. the computer wouldn't boot no signal on screen. Kept trying to make it work reseating other fixes.. tried my 960 again and it worked...