Bad video card or what?

Hi just need a little help. Having a problem with my pc. It was working good until the monitor showed my realtrek saying that something was unplugged, I ck it out and nothing was unplugged, I even updated the drivers just in case. Because every time I ck cancel it would not go away. The message went away for about 2 mots then it came back. Only this time my screen would go nuts;. The pic looked like you put it in a paper shredder then moved it out of sic just a little after that it would shut off and the monitor would say no signal. The pc would shut off and I would have to reboot it. This lasted for about 1week. Now I cant get any thing to come up. We have ck the cables,monitor and ever hooked the lap top to the monitor to see if it works.When we hooked the lp up to the monitor the screen was working fine. I was wanting to know if it might be the video card and how would I ck to see if this is it? My pc is a gate way,just off the shelf not very special but it works for me.") It is about 4 yr old. For any help I would be most grateful Thanks|||Tough to say. It definitely sounds like a hardware problem in your PC, though. I'd say 90% chance it's the video card, 10% something else. Only way to tell is to replace the card.|||I am not good at this, but before you replace the card

take your monitor and plug it into your built in graphics card (motherboard)

and plug the graphics card out to see what happens|||Sounds like a power supply problem. A computer that old you probably would do better to think about getting a newer machine. To replace it probably would cost you 50 bucks.