When you start your computer, hit DEL to go into the BIOS.
On the main BIOS screen, hit CTRL+F1 (this makes some hidden options available in the subsections).
Go into the Motherboard Intelligent Tweaker section. There should be an area with RAM timings - set them to 4-4-4-15 (I believe these are the top 4 numbers in the section - leave the rest on normal/auto).
Lower down on the same screen, there will be voltage options. You will likely have to turn off automatic or "optimized" voltages. Set the DIMM voltage to +0.3 (the "normal" voltage for DDR2 is 1.8V, and your RAM wants 2.1V).
Hit F10 and say "y" to save the current BIOS settings and restart.