Iamsoda :
tea urchin :
Consider;
Why would a power supply unit have been removed from its use?
Either the pc was dead (does not bode well for the power supply)
or the unit had to be replaced (bodes worse for the power supply).
Was the garage sale holder a qualified electrical engineer to HND or degree standard?
If not it is unlikely the unit had been 'reconditioned'.
Its been kicking about in a box for some unknown reason until you came across it and I really would not chance a heap of expensive pc components on it if I were you.
Best option is take it into a local pc shop and ask them to try it for you.
That is an interesting solution.
I can tell you there is nowhere in London that would do that. They will fire it up and measure the voltages but connecting a motherboard and other running parts? No way, Hosay!
Absolutely no 2nd hand pc parts shops sell used psu's or mobo's, either.
It just costs them too much in refunds.