8gb installed available 4gb


Nov 22, 2010
Hey people, today i received my new memory, i purchased:

Corsair XMS3 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit

Now i already had the 4gb version of this with the intention of running both , so 12gb in total but my pc wont boot with all of it.

But also when i just use the 8gb it says only 4gb usable and the other 4gb "hardware reserved"

So firstly, am i able to run both at same time.
And secondly, how can i make it so it isnt reserved.

I currently use win7 64bit

And my motherboard can go handle upto 16gb of 1600mhz memory.

Hope someone can help, thanks


Nov 22, 2010
Ok so ive tried it and it boots up with both of them individually, the only difference is that the 1 stick wont boot in the first slot unlike the other stick which will boot in either of them if that helps....
No, 1 stick should use the 2nd DIMM slot from the CPU; DIMM_A1

Just to check, use only the following DIMM slots:
CPU: | blank | 4GB | blank | 4GB | ; Blue DIMM slots only

Intel Core i5-760 2.80 GHz

Assuming - CORSAIR XMS3 8GB (2 x 4GB) DDR3 1600 CMX8GX3M2B1600C9
9-9-9-24-2T @ 1.50v

Assuming - there's no bad stick.

AI Overclock Tuner -> Auto
DRAM Frequency -> DDR3-1600
DRAM Timing -> Manual
DRAM RAS to CAS -> 9
DRAM RAS PRE Time -> 9
DRAM RAS ACT Time -> 24
DRAM Timing Mode -> 2N
IMC Voltage -> 1.20v~1.25v
DRAM Voltage -> 1.50v~1.55v

If the problem persists then IMO update the BIOS to Version 1504 using ASUS EZ Flash 2:
EZ Flash 2 is a built-in App to allow the BIOS to be upgraded and USB Flash Drive is the storage for the BIOS ROM file to be stored/accessed from with BIOS EZ Flash 2. The USB Flash drive must be formatted in FAT-32.

Link -> http://vip.asus.com/forum/view.aspx?id=20070215223109668&board_id=1&model=P5B+Deluxe
Video -> http://www.youtube.com/watch?v=NQKQj_aASCQ