The moment I began reading your post I thought PSU. Looks like you need to replace it to me. Be careful as some of the older Optiplex pc's had PSU's that were wired differently to the norm. If you should need it, I have all the wiring info to allow a standard PSU to be modified. :)
Rik from RCE
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If the mobo has the socket for the 4 pin then it is undoubtedly needed.
Can you take and post a photo of the psu plug as it is at the mo?
I will just add that psu's are my particular specialty.
Rik from RCE
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Hmm, it's a very awkward shape. It does look as if it is wired the same way as a standard PSU but you will never fit an ATX form factor one in there.
If you have a Digital volt meter I can give you instructions on how to test the PSU. It is still possible that the fault lies on the mobo so you need to know one way or the other.
Rik from RCE
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The current PSU is a 160W Dell Model # PS-5161-1D1; like I said I don't believe this is the one that came with the machine. Hope this helps.
the 4 pin plug is referred as the P4 plug and it needs to be plugged into the board or it will not boot,fans will run but that's it .
I buy and sell computers get most of them from this site ,I have owned a lot of this type of computer ,the psu in yours looks like the right one ,may not be original!
I live in Canada ,you can get the whole desktop unit for 68.00 + shipping . http://www.vfxweb.com/index.php?productid=11516
caperjack
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The thing is, to fully test a PSU you need to do on and off load testing.
I have come across a fair few PSU's that appear fine with no load on them but then break down when loaded.
Rik from RCE
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I am really not sure that a machine of it's age is really worth all the hassle to be honest.
Rik from RCE
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