I have recently been given a Pentium 3 800MHz with 128MB memory. It has 3 memory slots on the mother board and I have installed 2 by 256MB memory cards along with the original 128MB card. However all I get is 384 MB total RAM eg 3 * 128 MB. not the 640MB I expected. Is there a limit of 128MB per slot on a P3 mobo?