MBP: Why is only 3.72GB of RAM usable in Windows 7 x64?

Discussion in 'Windows, Linux & Others on the Mac' started by cool8man, Jun 24, 2009.

  1. cool8man macrumors newbie

    Jun 24, 2009
    Just installed Windows 7 x64 on a new Macbook Pro with 4GB of RAM. When I go to check the specs it says "Installed memory: 4.00GB (3.72GB usable)"


    Do I need to update a driver or bios?? My first thought was that it was sharing video memory, but my previous gen unibody Macbook has 2GB of RAM and all of it is usable in Windows 32-bit, none of it is shared. Both Macbooks have the same GPU so why isn't the total amount of RAM usable in x64 version of Windows? :confused:
  2. rgarjr macrumors 603


    Apr 2, 2009
    Southern California
    I dunno but mine has the same thing as you man. Not really concerned about it though.
  3. Gav Mack macrumors 68020

    Gav Mack

    Jun 15, 2008
    Sagittarius A*
    It's probably the 256Mb of video memory allocated for the 9400M GPU which Windows can't see or use because Apple haven't created a Windows driver to access it via EFI.

    You only had 2Gb ram in your previous setup, my uMBP running 7 32 bit says I can only use 2.98 Gb out of 4Gb but that's normal for 32 Bit Windows.
  4. cool8man thread starter macrumors newbie

    Jun 24, 2009
    Yeah that must be what it is. The previous macbook had Vista so I guess Vista just didn't report usable memory, only total memory and now Windows 7 indicates usable memory.

    Now I just have to get a driver fix for the speakers, the mic, the audio line out, and the keyboard backlight and I'll be all set. :D

    Very happy with the new Macbook though. I was able to have Slingbox HD stream running at 1920 x 1200 on an external monitor while browsing the web on my macbook screen without any hick ups.

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