It should be noted that q650/700/800's don't suffer capacitor leakage because they already have tantalum caps, that being said if you can't figure out what's going on:

http://www.ebay.com/itm/APPLE-661-1676-820-0380-04-QUADRA-800-WOMBAT-SYSTEM-BOARD-WITH-CPU-W-WARRANTY-/141592585530?pt=LH_DefaultDomain_0&hash=item20f793653a

The Q800 and Q650 have the same board... I have a spare Q700 board and that would also fit if it might help you...