I don't know much about the BIOS despite building a couple of computers but thanks to the people in this forum I finally got the BIOS flashed using a bootable CD. The BIOS now shows 4 gigs of ram but Windows Vista Home Premium 64 bit still shows only 2.5 gigs. SiSoftware also shows 2.5. CPU-Z shows the whole 4.
How do I get Windows to recognize and use the 4 gigs that are installed?