Hi, I have an ASUS P5VD2-X m/b and, according to the user guide, the '2 x 240-pin DIMM sockets support up to 4 GB of DDR2 533 unbuffered non-ECC memory'.
I have inserted 4 GB of such memory in the two slots (2 x 2 GB) but, according to BIOS, there is only 3 GB RAM available for use. Everest...