My computer Black outs after 15 mins

[Tanner200]

So I installed a new Hard Drive and new Windows 8.1. While Downloading Windows it Black out. By black out i mean everything is running but my tv has no signal.(i run through a tv hdmi) Luckily windows restarted my computer for a install. Everything was going good I installed windows 8.1 and the new hard drive. But still after 15 mins it black outs no signal to tv but all the power lights are on. My computer hasnt been on since 2010 the other day i said i was going to fix it. It will run for days but cant hold a picture. is it my power supply thats making it cut out or something else. Like i said it runs great for about 15 mins and then bam cuts out, lights are on but no one is home.

 

[Regularjake55]

Might have something to do with a gpu or psu but since it has to do with the fact that the TV isnt getting a signal I'm going to tell you what happened with my computer, ok so I have an R9 270 right and so I plugged it into my TV via HDMI and it wasnt getting a signal but if I connect it to a monitor it works fine so maybe you just need a new monitor? But still idk