iMac 12,1 21.5" (2011) Graphic Card Upgrade

Discussion in 'iMac' started by gotofbi, Aug 14, 2013.

  1. gotofbi macrumors newbie

    Nov 28, 2011
    Hello, I am really interested upgrading graphic card for lovely 21.5" iMac graphic card.

    There is already known post regard upgrading same model as mine but with 680M

    However, there are few downside with following post
    1. Losing initial boot screen (due to incompatible VBIOS)
    2. TDP and power consumption.
    3. Pricy! (about $500+@ on ebay)

    So, I decided to approach in a different way by using Geforce 660M

    There are few reasons that I decided to use 660M
    1. 2012 iMac is using 660M (512MB but still same chip)
    2. Low TDP
    3. Cheaper (about $250)

    Before I approach this major task, I am missing only one piece; iMac 660M VBIOS

    I was searching in the web for few days and I failed to achieve the VBIOS.

    So, if someone can please provide me the iMac 660M VBIOS, I will proceed upgrading and post results of upgrade

  2. gotofbi thread starter macrumors newbie

    Nov 28, 2011
    Ive been googling around to find rom for 660m but still didnt find anything.

    I was searching GPU-Z database and found few versions of bios that can be used.

    APPLE 660M

    APPLE 650M 80.07.1d.04.01
    APPLE 650M 80.07.1d.03.01

    APPLE(r) 650M

    If anybody can provide any of bios, that will be great.

    Thank you
  3. gotofbi thread starter macrumors newbie

    Nov 28, 2011
    I dumped Apple Kepler BIOS from iMac (21.5-inch, Late 2012) IM131.010A.B05 (EFI 2.0)

    However, this is partial BIOS and I dont think it will work as is since its missing some of header.

    When I open with nvflash --version, the bios does not display any information.

    I believe this is because the file is missing some header information(0x300~0x400 bytes of header)(non-efi bios has 0x300 bytes of header, and efi bios has 0x400 bytes of header)

    However, I was able to open it from Kepler BIOS Tweaker v1.25.

    I guess, If someone can mod this BIOS add some header information, It will work on any Kepler Video Card

    Hopefully someone can actually reconstruct the header of these bios so it can be flashed with nvflash

    NVIDIA GeForce GT 640M 80.07.4F.02.01
    NVIDIA GeForce GT 650M 80.07.4F.01.02
    NVIDIA GeForce GTX 660M
    NVIDIA GeForce GTX 675MX
    NVIDIA GeForce GTX 680MX

    Attached Files:

  4. VicLev macrumors member

    Jun 6, 2013
  5. VicLev macrumors member

    Jun 6, 2013

    maybe you have the 7xx vbios dumps? these actually are legit vbios for the kepler cards, they even can be edited by kepler bios tweaker, will try flashing one of the 660m or 675mx that are coming my way with apple vbios and see if that will run in imac 2011
  6. Fl0r!an macrumors 6502a

    Aug 14, 2007
    Those vBIOS files don't contain any EFI, like the one in the other thread. In best case, flashing one of these will not brick your card.
  7. frets macrumors newbie


    Jun 26, 2016
    has anyone had any luck upgrading to Mac OS Sierra whilst using a GTX 780m chip??

Share This Page