I have had an intermitent problem with on of my mobile rackmount computers, It runs and starts great for weeks at a time but everynow and then when starting it up after transport to another location it will not start up, we get no bios screen and it will read "no video input" on screen, black screen. We change cables to screen same thing, we change screen same thing, We open the case and the vid card seems to be seated properly but after we remove the card and reinstall it the computer starts normally and runs that way for a few weeks again.

3 times it happened at the same place, thier voltage is real low between 104 and 110 usually and I figured it was from the low voltage down at the 104 mark that might be causing the problem at first but it happened the other day at a location that had a solid 122 volts.

I am back to thinking it is a vid card or vid card socket problem, I tried to create the problem by wiggling the vid card in the socket and was able to get it to not post to bios, a black screen, one time it did post to bios and just before it went to windows screen it went black and did not come back on. I switched the monitor cord to the on board video and it was working, so some how it jumped to the on board when it went to the windows screen.

Right now it is again working fine and has started and stopped many times over the last couple days. I have ordered a new Video card to try (I have 3 identical machines I have put togeather with the same ATI Saphire X1650Pro 512MB AGP cards in them so having a spare will not hurt) I will also search for another MotherBoard for back up and to see if it is the problem if the new vid card does not clear up the problem.

The specs are:
Windows XP home /sp3
Biostar P4M80-M4 Mother Board
Intel Pentium 4 3.0 Prescott 3.0GHz 1MB L2 Cache Socket 478 89W Single-Core Processor
2 - OCZ Value Series 1GB 184-Pin DDR SDRAM DDR 400
ATI Saphire X1650Pro 512MB AGP Graphics Card
M Audio Audiophile 2496 PCI Audio Interface
Monitor is a 15" LCD Screen, not sure on that one what brand it is.
Again the unit has worked fine for a year or so and over the last 6 months it has acted up 4 times, not counting the times I created the problem.

Any other thoughts on the problem ?

Most likely you are having bad connectivity with AGP slot. If there is some oxidation on the bare metal connectors, best thing to do is to take some fine sandpaper and try to polish them out. Don't push too hard and don't use rough sandpaper. Most VGA cards have gold-plated surface, and you don't want to remove that protective layer.

I have used an eraser to clean the Video card connection 2 days before it failed for time # 4, could try some 800 grit wet dry paper lightly on it. I am not sure how I would clean the socket on the motherboard .

Socket is a different story.. I wouldn't advise you to try that. You would risk some serious damage (mechanical).

I think you've got all the swap around angles covered so that you can eventually narrow it down to either the card or the mobo. If it's not the card, I wouldn't p*ss around with the mobo if you're not happy with fine soldering. It could well be a dry joint under the AGP slot as Chaky has suggested.

I dropped in the new Vid card yesterday, it went out to the venue tonight, we'll have to wait and see. I am getting at least one replacemnt board to have on hand and that will be changed out if it still continues to act up.
Thanks for the input.