I just replaced anoisy power supply in this P3 L1000R. Now nothing will work. The MB does have the green LED light come on, but nothing else shows any signs of life. None of the fans (OEM and aftermarket) turn on. Is this motherboard dead? I replaced the new power supply with the old, and the result is the same. Where can I get a replacement MB? Dell doesn't seem to have this MB anymore. anyone kow of a place that will? Thanks for the help.

if this is the Dell I am thinking of then (from having to replace a faulty PSU myself on one) they use a PSU that has different wiring to generic ATX power supplies. Also they have an extra connector on the motherboard.
So there is the 20 pin connector which has non standard wiring to it
and another connector which i think was white plastic with maybe 6 connections in a row.
Does this info help solve it?

Well last night, I got home from work and tinkered with it some more. They do indeed have a 20 pin and 6 pin power connectors, but the new power supply, that is supposed to work in this machine, has an extra 4 pin cable for power and another extra small 4 pin connector for video. In any event, I reconnected the old power supply again, and it works. It is on the way out since after a while it starts this grinding sound with the built-in fan. So I think the power supply I bought is defective. I just don't know if these extra 4 pin connectors make any difference. I don't thik they should, but I have not run into this before. Thanks for the asistance.