Have ProComp mobo model bvc3a with VIA chipset running a 500 mhz celeron. Put it together a year or so ago with 64 megs of ram. Upgraded to XP and got a 256 stick of memory. System would not see it, only showed the 64 mg. Removed the 64 stick and tried just the 256. Computer only beeps at me. Took the 256 back for testing but it checked out ok. I traded it in for two 128 sticks thinking that would solve the problem. No such luck, same situation. Even tried in all slots just one stick at a time. Occasionally depending on the speed I specify in the bios it will show the 64 and 256 combined as only 16 megs. According to manual I have what is acceptable. I sure would appreciate any insight you might have.