Re: Dead PSU or Motherboard?
Difficult to say really. If the PSU had the correct connectors then it should power up the mobo. What vid have you got in the dead PC, is it 1 that needs a separate power connector, if it is then could account for the loud whine. You also need to test all the components from the dead PC 1 by 1 to see if they are working.
Re: Dead PSU or Motherboard?
Dell PSU's are invariably non-standard. They may look like a regular ATX one, but the pin out is usually different.
They have to be the most custom and bespoke machines ever!
Cheers,
Stephen
Re: Dead PSU or Motherboard?
Can you post your full system specs including PSU make and wattage and OS please. It sounds like a dead PSU rather than motherboard. Does the PSU smell of "burnt electrical smell"?