If the board says it will run 800, then pc6400 should work. But don't expect that much difference performance wise. Don't pay more for it over pc5300. I still recommend you match the brand and speed, unless you buy it locally so you can exchange it. Frys has a 15 day return policy with no restocking fees, but their stores are mostly in the west southwest and atlanta areas. Microcenter may have a similar return policy, but check with them first.