Hmm....very strange...saw screenshots of the bios that showed the memory timings and the CPU/AGP voltage settings but no memory.
looks like the changes are not made through the bios but through the speed gear windows overclocking software. Check page 55/56 of the manual.
"There are three meters showing the current
Vcore, Vddq, and Vmem, each with a reading
on the bottom. There is a small yellow triangle
arrow below one of the meters.
You can click on the handle bar on the right and
hold the mouse button down to change the
voltage of the meter pointed at by the triangle. If
you wish to make changes to a different meter,
simply click on such a meter, then the triangle will
move under the meter you just clicked on."