Hello, I am posting here after much searching and little success.

Specs of computer are as follows:

Intel Pentium D 820 2.8 Ghz Duo
Intel Motherboard BOXD945PSNLK
Crucial DDR2 2 sticks (512 MB)
Power Supply Antec SP-500
Case CoolerMaster Centurion 5 CAC-T05

I am one of many building these machines for an organization, and the issue I have run into is:

Computer is built, powers up, and runs normally. We always flash the motherboard bios to the latest version once we have verified the computer works properly.

Whether or not I flash the bios, and whether or not the computer is left running for 20 seconds or 10 minutes, the issue has arisen in over half of the machines I have built that once I hit the power switch to turn the machine off, it will never turn on again. Nothing happens. The green light is on, but no fans start ( not even briefly ).

Swapped out all parts except board, doesnt boot. Switch boards and will boot once, then fail as above. Take board out of case set on static bag, doesnt boot. Tried to boot with only memory and processor, doesnt boot.

(Doesnt boot means absolutely nothing happens when switch is pressed)

Tested power supply independantly by using paperclip on 14 & 15.
Also have used at least 3 different PS.

I have arrived at a situation where I can get the motherboard to turn on (fans spinning on case, board and processor as per normal boot) if I use a paperclip on 14 and 15 while PS is connected. Testing the power switch pins yields nothing with same paperclip. It seems to be an issue on the motherboard itself. Is there anyway to further isolate the problem or otherwise work around this situation?

I have used a voltmeter to verify that pin 14 is at 5 volts, and pressing the switch does not change this reading (dropping it to near 0 as it should) My theory is the power supply is frying the board but I cannot really prove this (any suggestions?) and we must have several of them. My other theory is that we have a bad batch of boards (any suggestions for proving this?). My most popular theory is I am doing something wrong occasioanlly in my process, but have examined it thoroughly and have had others do so was well. One other person had this issue, but I am the only one to have it repeatedly.

I have succesfully built 6-10 computers with these parts (old parts), but over 50% of my *new* finished builds have this issue. These new builds are with a new batch of parts.

I am hoping some out there are looking for a really tough problem to help solve, any help is appreciated. Thanks for your time.

Can I clarify whether or not one of the boards - after it has failed - can be used again once if it is removed and used in, let's say, a new build?

Or is the problem resulting in dead boards?

The board will not work at all if moved to a new build once it has failed. So far the only way I have found it to work after first boot is w/ the paperclip solution.