system won't boot

I've had a problem booting up my system for days now. I turned my computer off and when I restarted, it won't boot up at all. The fans do spin but I get no signal on my monitor and no beeps. The strange thing is that I've done all the following steps and it hasn't helped at all:
- replaced the power supply ( the power supply wasn't working properly but even after installing the new one I still have the same problem)
-replaced the original Ecs K7VTA3 motherboard with a matsonic MS8177C+ and then with an ABIT k7V and still had the same exact problem
-tested the 2 different DDR PC2700 memory sticks on my other system and both work fine
- Tested the video card and it runs great on the other system.
- Replaced the AMD XP 2400 with an XP 1800 andd then an Athlon 1 GHZ and still the same problem.
I get no beeps and no video signal still. I would really appreciate any help with this problem.
CaliHank

Check your IDE cables. If one of the cables is loose on one end it can give that sort of problem. I say that because I had a similar problem and the IDE cable to my HD was a tiny bit loose. I'd even change out your IDE ribbon cables and check the pins on your HD. Maybe one of the pins is broken or bent. Also make sure the power plug is in good on your HD. Hmmm, I guess since you changed PS, you did that already.

thanks for the response lennynj99. I FINALLY figured it out. The case's speaker wire was loose and apparently causing the problem. I installed a P4 with an Albatron 865PEPRo yesterday and so far the system's running great. I'm so glad it's finally over.