I wished to upgrade my ram from 2 to 3 gig. I currently have 4 512 ram. When I remove 2 512's and add 2 1gig my computer only reads 2.5 gig when it should read 3 gig. I have made sure all ram chips are good. I have moved them around. I added them one at a time to confirm that each was read. When I install the last one it stays at 2.5. I have an Asus Motherboard. I have also confirmed that I have the right speed ram. I am running xp.