Desktop

Have you double checked your motherboard jumper settings.
~Does The Problem Still Occur~
List all Cards in the computer starting from the top to the bottom and try the computer after removing the 1st card then try with the second card. 1 at a time(note don't remove any important cards i.e video card)THE PROBLEM COULD BE A CONFLICT
If this doesnt help you e-mail me at hauber@btinternet.com and i'll put more thought into it

Wow! What an ordeal... you've done all the things I would have done but it sounds like a motherboard problem. If both motherboards you tried were the same make and model, I would think that a configuration error is the most likely explanation (CPUor bus speed are two common errors) although I did once get two defective motherboards in a row.

My only suggestion would be to really take it back to basics and start first with only the power supply, motherboard, keyboard, video card and floppydrive and see if it will boot to DOS. Then add the hard drive and then finally the CD-ROM and see where it stops working.

One of my colleagues at work had a similar problem that turned out to be a defective IDE port on the motherboard which sheconfirmed by using an ISA IDE controller that worked fine.

paul

Since you've already tried everything else, it's got to be something on the MB or an add-in card. Remove all add-in cards except the video card, and see if the system boots. If not, it's got to be something on the MB. If you have KB, Mouse, videoor other integrated peripherals, it could be something is shorting out or not properly connected. Could be jumpers, too. If you've checked all these, I'd say the only thing at that point is to just replace the MB itself. Good luck!

Possibly the cable between the motherboard and the hard disk is faulty. One of the wires may be broken. Try replacing the cable with the known good hard disk and see if that works.

clover

Sounds wackey!

Are you useing on board video? Are you sure the motherboard jumper settings are correct? Is the CPU registering at the right speed?

My money is on the video card. Either bad memory, conflict or configuration.

Good luck!