Windows using only half the physical RAM

Hi all,
I had a set of 2x2GB G.Skill F3-12800CL9-2GBNQ running fine for around a year on default XMP settings, and just installed a new pair of these alongside them.
The system is now
i5 760k (no OC)
2 sets of the above mentioned for a total of 8GB RAM in 4 sticks
GA-P55-USB3L with latest BIOS (version F8)

The system is fine, except it doesnt seem to use the 8GB.
The system panel (the one that I can get to by rightclicking my computer and clicking on properties) says I have 8GB physical memory and that Windows can use only 4GB of it.

So far I've tried disabling XMP and setting the memory setting manually to the product specs (9/9/9/24) on both channels and increased the DRAM voltage to 1.6V, but still no luck.

Any help would be greatly appreciated.
4 answers Last reply Best Answer
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  1. Best answer
    Since I cannot read those 'ideograms' if the Windows 7 Enterprise is a 32-bit version then 4GB is the max; you need a 64-bit OS to use >4GB - I see what appears to be '64'.

    Never use XMP on more than (1) set.

    Don't mix sets in DIMM slots; install as:
    CPU: | Set 1 | Set 2 | Set 1 | Set 2 |

    Clear CMOS use the Jumper method -

    To see if you have a 'bad' stick boot with (1) stick at a time, then test (1) Set at a time by itself.


    If none of that helps then let me know. P55's are notorious for bent CPU pins and 'lost memory' is a typical issue. Also, if you have an aftermarket HSF then make sure there's no Metal -> MOBO contact.
  2. Thanks for your post, jaquith
    I've tried the one stick at a time approach, and kept getting rapid beeps, which the mobo manual said was bad RAM connection, and that I should try applying more force
    I did exactly that, and the rig is working perfectly now
    Apparently, the issue was that the new RAM was just not put in hard enough to begin with.

  3. Best answer selected by jkih0021.
  4. Yep good seating always helps! :) Thankfully it was a simple fix!

    Take Care!
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