Which bios are you running? Mr Naturals TH7H_7D is what I use. He has all of his bios posted here,
http://www.n3dt.com/drivers/bios/abit/th7ii/
Also I suggest only running the two single sided rdram sticks in the slots closest to the cpu and have your fan blow onto the sticks as well as the drcgs which are very close by, put the fan close to them. What is the date marking on the memory?
Older sticks don't overclock that good to PC1066. Mine say Samsung Korea 0151 which means week 51 of the year 2001.