New Graphics Card for iMac

Discussion in 'iMac' started by Broozeb, Jun 2, 2014.

  1. Broozeb macrumors newbie

    Jun 2, 2014
    Hey. I have a 21.5" iMac. Here are the specs:

    Processor: 2.8 GHz Intel Core i7
    Memory 8GB 1333 MHz DDR3
    Graphics: AMD Radeon HD 6770M 512MB
    Software: Mac OS X Lion 10.7.5

    From the heavy 3D gaming I do and the low FPS I get, I highly doubt it's the processor's fault, I think the measly 512MB graphics card is to blame, and so I'm looking to replace it. However, I really have no idea where to start, so I have a few questions...

    • Does anybody know if I could replace it myself?
    • Where to buy a new one?
    • The cost?
  2. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Yes, but the process is not easy at all. You only have very limited choices, and if you damage anything during that complicated surgery, you may end up brick your iMac.

    Since you have absolutely no idea where to start. I assume that you are not an expert of upgrading these kind of all-in-one, computer.

    My personally suggestion is don't do it. Too risky for you.

    Anyway, I agree that the 6770 is far from decent for heavy 3D gaming. Most likely that's the bottle neck rather than the CPU.
  3. mad3inch1na macrumors 6502a

    Oct 21, 2013

    Here is an apple forum thread that kind of answers your question. Basically, you can only upgrade to one of the cards you can get upgraded by Apple. It will cost you hundreds of dollars, be really hard to do, and will provide little to no benefit performance wise.

    On another note, your VRAM is almost certainly not the bottleneck. The GPU itself is most likely a bottleneck more so than the VRAM. Currently, the gtx 780m in the maxed out iMac has 4GB of VRAM, and any AAA game will not even use half of it. The GPU itself will bottleneck first. You may already know this, but the VRAM is almost entirely devoted to loading textures. If your VRAM fills up you will get huge lag spikes, but 512MB VRAM is more than enough to match the graphics power of the 6770m. If you really want to make sure that VRAM is capping out, turn off AA and any texture mods then check if your performance increases that much. It should jump from 15-20 fps up to 60-80 fps.


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