Thanx milesofwire and Digi for getting back to me.
"If it's obvious then it's obvious." Same problem, same hardware~ the power supply must be the culprit. Tech support at SBS said the same thing suggesting that the d24 card and farms don't need the 3.3volts but the Mix card does. (Digidesign, is this true?) I will double-check the voltages to ground using this pinout chart---
http://pinouts.ru/Power/atxpower_pinout.shtml.
Thanks again!