At Monarch Computers if you select the A8N-SLI Premium from the config page a popup tells you that this board does not run with 4gb and suggests the A8N-Sli Deluxe.
I would check there to see the exact ram they where using...
Exact same problem here.
Bios will not fix it, dump it if you can !
Call Asus and let them know about this problem so people like myself that are stuck with board can get a exchange or something...
http://forums.amd.com/index.php?showtopic=63530&hl=