I run 2.9 24/7 on stock cooler. Put your fsb to 290, underclock your ram. These chips will most likely always do 2.8-2.9 stock vcore. Anything after that then consider yourself lucky. Why stop at 2.6 when you can have it at 2.8-2.9 on stock vcore.
Edit: I think you have to hit ctrl+f1 when you get into bios for your board. That might be for timings but nonetheless do it anyways. Make sure to set the right divider for your ram. If you have ddr2 800 try to keep as close to that. Unless you want to oc the ram too but thats a different story