Best place to look would be the Abit Forums mate, or drop their techsupport an email.
Not sure how many people here have that chipset, Abit are not as renowned as DFI for producing memory specific BIOS - that being the case, if it were me I'd use the latest and then work my way backwards until I found one my rig likes.
Sorry I cant be more help.
Good hunting my friend
Mav