Flashed the BIOS, can't increase memory speed

[CliffyG]

Had some strange hangs in the bios so flashed to the latest version to see if that helped. All seems ok apart from 1 thing, previously i had my speed in the bios set to DDR 800 (using 2 x 512 Geil 6400). All i did was set it to manual and changed the 1 setting from 633. Now after the bios flash when i make that change it just beeps at me and doesn't even post. Any ideas?

 

[CliffyG]

Sorted it out by increasing the voltage to the memory to 2.1v. I understand i need 4-4-4-12 timings with this memory too but have no idea which bits i'm supposed to be changing in the memory options part of the bios.