I just recently built a new pc and added 4GB G-Skill DDR2 800 Dual-Channel memory. On the post screen, the bios recognizes the full 4086MB. Sys info only recognizes 3.5GB of the memory, yet my diagnostic tools say that my PC is running on 2048MB. I've been searching, and reading, a lot about this issue, and I don't fully understand why it's doing this. Windows XP Home SP2 AMD Athlon 64 X2 6000+ Gigabyte Mobo Heeeelp! Thanks in advance guys.