Showing 5GB instead of 7GB

Noorbakhsh

Honorable
Jan 22, 2014
18
0
10,510
Hi everybody!
I have faced with a problem. I have installed 3*1 + 2*2 GB of Corsair memory on my mobo, and CPU-Z shows 7GB, but windows 8.1 64bit and bios show 5GB. When I change the slots it shows 7GB but after some restarts it shows 5GB again. What is the solution? Thanks for your help.
ASUS P6T DELUXE V2
Core i7 920
Corsair XMS3 DDR3 1600