I Changed My Graphic Card Now The Computer Only Runs For 5 Seconds
I recently changed graphic-card because I had some problems with games, the graphics were flashing and I though it may be the graphic card. When I was going to remove the old card, I used a screwdriver to wiggle the safety so I could remove the card. The screwdriver slipped and I touched the motherboard a bit... There was no "stuff" there, just a smooth plastic surface.
I removed the fan for a cleaning, then placed it back. When I start the computer... it's on for about 5 seconds, then it turns itself off.
This could be any one of the hardware components causing this, but because the problem started when you worked with the video card, lets start there.
Check to see if you unplugged any of the fans in your case, push the power button again and see if they all come on. If they don't, that is your problem.
Make sure you connected the power wire back up to your video card if it needs an additional power source.
If you still don't have any luck, it's now time to start swapping out parts to eliminate what is causing the system to shut itself down. Start by swapping the video card with a friends, or a spare. Next in this case, I would try a different power supply. After that, individual RAM sticks. By this time if you haven't found the problem, it is likely the motherboard.
Sadly, out thinking this problem is much harder than swapping out to see what is causing the problem, and the just replace that part. If you don't know a friend you can swap parts with, talk to your local electronics store. They often have test units you can borrow for a couple of bucks until you find what you need to replace.
Also, if you get any beeps when you boot, write them down so you can check the beep codes, they will tell you why the motherboard is turning the system off.