I recently rma'd my gpu as it started to show artifacts. Received a replacement card and it worked for about 3 hours without a problem, but then it suddenly crashed to a black screen/vertical colored lines and the fans went full blast. Since then, I have had the system simply fail to boot with the card installed, fans go full blast, but other times I can get it to boot fine and run for hours without issue. It can even crash while simply sitting in the bios screen. It's completely erratic behavior. I want to believe it's simply the gpu, but I've read its possibly my psu simply not giving the card enough power at times. Any advice would be appreciated.
Gpu: xfx r7 370
PSU: thermaltake toughpower gold 750w