I suggest testing the motherboard with minimum components (one memory stick, no graphics or add-on cards, no drives) out of the case, on a non-conductive surface.
Remove power and CMOS battery for twenty minutes. Try another power supply if possible. Do you get three beeps with no RAM installed?
Thanks for the suggestions. It took me a day to locate a suitable power supply to try, but no dice. Same problem: E6 and 2-4-4-2 beeps. I'm really confused by the beep codes as 2-4-4-2 sounds like a Phoenix code, not an Intel code.
To answer your questions, I am trying with nothing connected (no USB nor video headers used), no cards (except video) and yes, I do get 3 beeps with no RAM installed. I'm coming around to the board being bad, but I wanted it to work and felt I should try everything. Any other ideas, or I'll just toss this one on the recycle pile and get on with other things. Thanks again.