Asus Rampage II Extreme, compatible with Dell Perc 5/i

There's a weird problem, though. The latest BIOS versions (1204 and later, it appears) cause the board to detect only 4GB of RAM (out of 6) in the presence of the RAID controller. Take the RAID controller out or downgrade the BIOS and all memory is detected...

Friend replicated this in his P6T WS Professional