I think it's the power supply...

[HayZee518]

pwer supplies

the power out of the four pin molex plug is 5 volts dc.
if you have a sata system then the old power supply won't work even though it may look the same.
the old system used a parallel interface which is the flat cable assembly coming off your hard drive and may be piggy-backed to your cd drive.
a sata system uses a whole different cable.
check the wires and look for a very small molex connector marked P1

[mrcaptainbob]

I have a Dell Dimension 2350. Yeah, it's old, but it works fine. Except after the lightening storm a few weeks ago. Although it was plugged into a spike protector power strip, one of those for computer use(!) the darned thing won't fire up. Despite the fact the strip was shut off at the time! There is power from the supply cord, so I'm assuming it's the power supply that's been compromised. But....How can I verify it? I'm sure there is (are) power outs from it, but how can I check for voltage? And what should I expect? DC? 12V? 48v? ....?
I do have a 'spare' tower with a known good power supply. Can I swap them?