Question NEED URGENT HELP!!!

[nsmitthh]

So about a year ago, I got an old PC out of my basement. My Dad built it and he didn't need it so he said I could take it. It runs perfectly fine and honestly has been great. I first ran into problems last summer when the PSU began to crap out on me. It would randomly shut off and lose power, the weird thing is that it kind of has erratic patterns with the shutting down. Sometimes it'll shut down as soon as I turn it on, or it'll last an entire month. So last while playing a game it shut off, which I didn't care about because I was about to get off, the following morning I tried to turn it on and for about 3 hours it would turn on, restart within a span of 5 seconds to 10-minutes, each time happening randomly. Then it stopped, so I was glad about that, but then my video card wasn't working. This isn't the first time this has happened, I've tried switching video cards as well but nothing works. I feel like it's not getting power through the PCI - E cables, but the rest of the computer is. It would really mean a lot to me if someone could help me with this!
EDIT: I'd like to mention that the graphics card usually lights up, the fan is still spinning though.

 

[Zephyl]

Replace the PSU.

 

[DSzymborski]

You had a pre-existing problem with your PSU that you ignored. So now it's likely that either that PSU has died or a PSU that gave you ample warning there was something seriously wrong has destroyed another component.

Either way, as Zephyl said, the obvious first thing to do is to swap out the power supply. If your PSU was showing signs of problems last summer, it should never have been used again.