Computer Power Problem

Hello,
I am new to the forums and have a problem with my PC. I would appreciate any advice available. First I will describe my setup.
Gateway Desktop (purchased new in 2000 or 2001)
AMD 1Ghz processor
3x128MB Ram
500 watt power supply (newer)
EVGA display adaptor (newer)
38 GB hard drive
DVD-ROM drive
CD-RW drive
floppy drive
D-link USB wireless adaptor

This setup has worked well for several years now. But recently the computer has become very sensitive physically. If you bump the computer desk, the whole thing just shuts off, and you have to wait a moment with the power unplugged, in order to turn it back on. The monitor doesn't turn off just the PC. Also the computer will lose power momentarily, and everything freezes on the screen, but the power comes back on. Actually the whole computer doesn't turn off, the fan stops spinning on the processor, and then starts spinning again. So I have taken the computer apart piece by piece, and put it together again and it still does this. I have tried it with different hard drives, unplugged DVD, CD, and floppy drives, with one one RAM chip( tested each one) and it still does this. My video card and power supply are both fairly new. Should I test them? or is it likely a motherboard grounding problem? Or whatever? Any way thanks in advance to antone that read this and has any idea what I should do.

 

datawerd, Welcome to MG'S. I would check power supply,sounds like something is shorting out.Was your old ps bad,if not and you still have it I'd try it. I keep a good one around just for that reson. Chuck

 

Here a link on how to test a power supply. Hope this helps Chuckhttp://www.duxcw.com/dcforum/DCForumID3/447.html