i have 4GB of OCZ Reaper RAM

in the BIOS, it says i have 4GB, but in the system controal pannel, it says i have 2,5?

where is the rest of my ram?

is my 9800 GX2 FXF eatiing it all up?

i have a Q67000 (2,66 GHz)

780i motherboard

here are my system specs:

780i mobo

4GB OCz Reaper RAM

500GB harddrive

NZXT blackline case

windows xp 32-bit

9800 GX2 XFX 1GB Grapics card

10/100 interrnet

quadcore 2.66 GHz processor

when the bios starts up, it shows 4GB of RAM. but when i go into the controal pannel, it shows 2.5 GB or RAM.

where is the rest of my RAM???

e-mail: mattmansfirehole@hotmail.com