According to EVGA, it supports 1200 (OC) and 533/666/800 Native ( http://www.evga.com/articles/329.asp
). It should run 1000 MHz memory by overclocking but I won't run 1333. To be honest, I would stick with DDR2 800 for an older LGA 775. There is little to no benefit in going above it for that socket.