I would look for some used pc6400 ddr2 on craigslist. I found an asus am3 board with 4 gb of pc6400 for only $35 recently. It works fine. The board limit is 2 gb per slot, or 8 gb total. To overclock the cpu, drop the ram setting to 667 and increase the cpu fsb by 20% for a stable overclock. You won't have to increase the voltage for this. With these settings, the ram will be running in spec for a net speed of 800. http://www.newegg.com/Product/Product.aspx?Item=N82E16813131045