You use an old BIOS or that board. Rev. F10 has been released for a while and it helps for overclocking, especially versus the pre-F9 releases.
The board model is the 965P-DS3 and I happen to have the same right next to me, with an E6400 on it. I have the PCB revision 3.3, you?
I'm sure you know, but you have a few more options in the BIOS if you press Ctrl+F1 while you are on the main BIOS page. Nevertheless, that's an impressive overclock out of this supposedly less overclockable CPU (Allendale is said to be less OC-friendly than Conroe).