Wont boot on 2 machines...

Hey,

My dad's been foolin around for a while buying bits and pieces to build a new desktop PC and upgrade an older one. He's had some of the components for nearly a year but never been used.

I sat with him today and went through a systemtic process of trying each of the components seperately to determine which was the faulty device, and possibly some idea of what was going on.

He has a brand new processor and ram for one of the machines, and a brand new motherboard but when we try to fire it up; the CPU fan spins momentarily and then the whole thing goes off. No beeping, no video, nothing. We attached the setup to another power-suply to check it wasn't the power and we got a constant on-off-on-off of the fans, which was quite scary.

We tried the processor, ram and video card in another motherboard (older, but still capable of running the components), and the power comes on and stays on... no video, no beeping. When the hard drives are connected, they all fire up and sound like they're going through their checks... but nothing after that.

My dad informed me tha the older board (paragraph above) was running fine for about a year, he'd switched out the processor for a newer one a couple of months ago and after a number of days it'd started shutting down or just powering off... this happened for a couple of days before packing in all together. ~ I presumed the processor was overheating and finally had enough. He tried the older processor back in there but that doesn't work either.

Just generally, I was wondering what the symptons are for this kinda problem where we dont get any beeping or video, or where it shuts off instantly as you power it up?

With a brand new chip and memory i'd tend to say the problem was with the motherboard, and with the other motherboard failing after the possible overheating, i'd say that this motherboard was damaged too. Can anybody confirm this or have had any similar problems?

Thanks in advance,
Regards,
Chris

For the first problem, with the instant shut-down, I would say there is something causing an overcurrent-- the power supply detects too much current being drawn and turns itself off to prevent damage... if you have to wait a little while before the PSU iwll try turning on again, then that would be a definate indicator of an overcurrent situation.

Overcurrent is caused largely by short-circuits, though if one has more devices than the PSU is capable of handling, then that could cause the problem, too. If the motherboard is installed, try running it up outside the case... make sure it is sitting on an non-insulative surfacce and see if it will turn on. Check the CPU fan, and see if it is working properly in a different system.

For teh second problem, make sure that you have a speaker connected to the motherboard or that the motherboard has an integrated speaker/piezo-electric element. No beeps generally means that the POST isn't happening at all, which would indicate a failure of the motherboard itself, the processor, or possibly the memory, though there should be a beep-code for missing memory, so that is unlikely. If the PSU isn't putting out all the correct voltages, then there might be a problem with that, too, though, again, that is unlikely.