Bad GPU or PSU?

[35g700]

Recently my computer has been rebooting during games, almost as if I hit the reset the switch, so I updated my drivers but it still shuts down after about 20-30 seconds of fur mark. I was about to buy a replacement GPU because my 970 is well out of warranty, but then I thought it might be my HX750 that is still under warranty. I don't have a good way to isolate either because the only spare PSU I have is 430W and I have no spare GPUs.

Has anyone seen something like this before? I am starting to think it's the PSU and not the GPU.

EDIT: I remembered I had a CX430 laying around unused so I used a molex to 6-pin and put in in my system and no issues under heavy GPU load. Looks like it was the PSU.

 

[PP Mguire]

Was gonna say the 430 is enough to get a good test in. I've used my eVGA 430b for this same thing before. That thing has actually held up to a Titan X lol.

 

[35g700]

Yeah the calculations for max output of my system is only like 350W. 430W isn't something I'd want to run for a long time, but I really only need like 550W max because I don't think I'll ever do multi-GPU again.