RJT> The PS is sitting here connected to *nothing*,  power cord
 RJT> in there,  jumper wire in the output plug,  and when I flip
 RJT> the switch I get absolutely *NO* response from the fan,
 RJT> not even a twitch.

IMO it would be better if you could test it with a known good
MoBo/system.  You said the board came from your brother?  Would
it be possible to get said PS next to his ATX box, unplug his PS
and plug yours in without installing it?  Small chance of messing
up his system, but gives you confirmation with a known good box.
Failing that, this Marl board uses ATX.

... Feel lucky????  Update your software!
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