Not sure that would make a difference. The whole rig runs about 1085 watts stable with 5 cards and has 1500 watts available. Plus they hardly use any power until they start hashing so it seems like it would finish the boot cycle before crashing? Any other ideas? or does anyone else think this is a power issue? Really stumped and willing to try anything. I will get another power supply tomorrow if I can't get anything else to work.
If you can't get the board to boot with 6 cards, it is not a power issue. Power usage probably no more than 400w combined for boot.
As far as hashing goes you might run into problems if you can't balance the load evenly. 550w (if split perfect) on each 750w PSU, adding another 250w card can possibly overload one of them.
Try updating BIOS. Which board, UD3, UD5 or UD7? Pretty sure this is a BIOS or hardware limitation. Gigabyte support is usually very friendly, just email them with your issue and they might even try to reproduce it in their lab. One of their guys pulled up a Rev 1.x UD5 for me to give BIOS screenshots when I asked about CPU Load-Line Calibration settings before purchasing.
