i have some reaper memory that was wrong when installed in the same
Are you running the ram in dual if so try it in single. Sounds strange but worked for me on my ram. (i am only on 2 gig ram though)
Also what os you using. Forgive me if you know already but i read that 32bit vista had problems with ram at 4 gigs.
Im using that board too.
dont know if this helps but just wanted to share experience