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2.99GB usable of 6GB total

I have 6GB RAM installed, and while 64-bit W7 recognizes all 6GB it only lists 2.99 as usable.

I'm using the vanilla Asus P7P55D mainboard, along with four sticks of RAM- two at 2048MB, and two at 1024MB.

I have memory re-mapping enabled, and 'maximum memory' in msconfig unchecked.

At this point, I'm guessing I'm dealing with faulty hardware but I thought I'd give the internet one more shot.

Any help would be appreciated!
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More about 99gb usable total
  1. Welcome to Tom's Forum! :)

    Mix-Matching RAM has it's risks and the solution might be to purchase a Fully-Matched Set. I would use BIOS version 2003 or 2101 and confirm the following are all as shown below.

    As a test, install only the 2x2GB set and make certain the RAM is properly seated and locked-in. Next in the BIOS press F5 (Load Defaults), change other required settings i.e. SATA-> AHCI (if used, etc) and F10 (Save & Exit):
    CPU: | blank | 2GB | blank | 2GB |

    Assuming you have 4GB then add the 2x1GB:
    CPU: | 1GB | 2GB | 1GB | 2GB |

    IF that fails then please post a link to BOTH sets of RAM.

    An important indicator is the amount of 'Hardware Reserved' - it shouldn't be >30MB~50MB if there's no onboard iGPU (video):
  2. Thanks a ton Jaquith.

    Before I begin, my BIOS version is 0209. Should I proceed with testing the RAM?
  3. I'd update your BIOS*, use ASUS EZ Flash 2 with a FAT32 Flash Drive; see -

    * Prior to updating the BIOS Load (Optimized) Defaults typically done by pressing F5 in the BIOS, then download the latest BIOS and unzip the (.ROM) file. copy to the Flash Drive and watch the video in the link above and if needed the Guide. The process is straight forward. Do NOT update the BIOS in any other way than ASUS EZ Flash 2!!!
  4. Okie dokie, just got home from work and immediately started working on my RAM problem.

    First thing I did is update the bios to version 2003. Went well.

    Then I installed just the two 2GB sticks. System recognized and used all 4GB, with barely any in reserve.

    Then I additionally installed the two 1GB sticks. System then recognized a total of 6GB, but only used 3GB- my original problem.

    The 2GB ram is Corsair CM3X2G1333C9, 1333 @ 1.5v

    The 1GB ram is Corsair CM3X1G1600C9DHX, 1600 @ 1.8v

    I'm running an i5 750 @ 2.6 GHz
  5. You are mixing both different Frequency AND Voltage RAM which is a really bad idea.

    You can 'try' to set the RAM manually:
    DRAM Frequency -> DDR3-1333
    CAS Timings 9-9-9-27-2N (CAS-TRCD-TRP-TRAS-CMD RATE)
    DRAM Voltage -> 1.55v

    F5 - Load Defaults
    AI Overclock Tuner -> Auto
    DRAM Frequency -> DDR3-1600
    DRAM Timing Control -> Manual
    DRAM CAS -> 9
    DRAM RAS to CAS -> 9
    DRAM RAS PRE -> 9
    DRAM RAS ACT -> 27
    DRAM Timing Mode -> 2N
    IMC Voltage -> 1.15v~1.20v
    DRAM Voltage -> 1.55v

    Save & Exit = Yes

    /No guarantees, RAM is dirt cheap!
  6. Should I just get two sticks of 4GB ram and use that instead? As you said, it is really cheap.

    Have I done any kind of damage by using mismatched ram for over two years now? As I was typing the voltages and frequencies for the ram, I figured that was causing the whole mess.
  7. Best answer
    IMO - yep get a 2x4GB set:
    $45 CORSAIR Vengeance 8GB (2 x 4GB) DDR3 1600 Model CMZ8GX3M2A1600C9 -
    $45 Mushkin Enhanced Blackline 8GB (2 x 4GB) DDR3 1600 Model 996995 -
    Both sets: DDR3-1600 9-9-9-24-2N @ 1.50v

    As far as damage - no. Yep, the mix-match is a PITA and even set manually as above might cause instability which is why you run Memtest86+ for 4-passes to overnight to 'know'.

    If it were 'me' one of the (2) sets above.

    BIOS settings for the sets depends on the CPU; for an 'i5 750 @ 2.6 GHz':

    F5 - Load Defaults
    AI Overclock Tuner -> DOCP
    DRAM OC Profile -> DDR3-1600
    DRAM Timing Control -> Manual
    DRAM CAS -> 9
    DRAM RAS to CAS -> 9
    DRAM RAS PRE -> 9
    DRAM RAS ACT -> 24
    DRAM Timing Mode -> 2N
    IMC Voltage -> 1.15v
    DRAM Voltage -> 1.50v

    Save & Exit = Yes
  8. Thanks a ton, Jaquith. I'll be picking up a new set of RAM shortly.
  9. Best answer selected by loganvh.
  10. This topic has been closed by Nikorr
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