I've originally had 512MB DDR PC3200 RAM and an empty slot. I bought a 1GB DDR PC3200 and recently installed it in the empty slot. When i boot up my computer it only says it has a total of 1GB RAM, and when I scan it with crucial it says that I have 2 slots both with only 512MB. I've tried using only the 1GB and leaving the other slot empty and my computer only says it has 512MB.