computer will not turn on...Major help needed

I came home from work and found my PC off. It was on when I left, and the monitor, speakers etc. were still on. It's a home built with a machspeed p4msd-800 board and a 3ghz dual core intel proc. Systematically disconnected all hard drives, floppy, cd-rom drives (power and ribbon), add on cards (wireless, lan, usb, agp) and then disconnected fans. Still wouldn't come on. I plugged in another known-working ps i had, same thing. The HDD light flickers once, the cpu and ps fan trip for a split second, then nothing. If I try to turn it on again nothing happens. I have to flip the main power switch on the ps off for about 10 seconds then on again in order to get the light to flicker and fan to trip when I hit the case power button again. If it means anything, I also pulled my proc. fan, then the processor itself and hit the power button, same exact thing. Do I have a bad board?? or is the processor burnt?? Please help, I do a lot on this darn thing and am in trouble. I have my notebook, but that has all my work stuff on it and I don't want to use it at home too often (3 little kids that like to play!!!)
Any help is appreciated, ty.

 

Well if it's not the psu, then the most likely suspects to check are the cpu and/or mobo. Could also be the board shorting out but I would say that this would be less likely. Also boards sometimes have an automatic shut off if the cpu fan is not detected.

Short of replacing or testing suspect components there is not much that can be done unfortunately.

Perhaps some users will have better ideas as to how to proceed.

Good Luck

 

I just went online and purchased an ECS p4m800t-m motherboard. Not top of the online, but great for the price and it matches a lot of existing hardware. (two IDE channels and 2 SATA connections and a socket 775 for my processor, so I hope to god thats still good lol. Still looks ok)
Any other feedback is still appreciated, thanks guys.