Relative GPU performance on 21.5" and 27" iMacs?

Discussion in 'iMac' started by chris1987, Jul 24, 2012.

  1. chris1987 macrumors member

    Oct 21, 2008
    Hi, i'll make this question as quick as possible - i was just wondering if there would be a noteable difference in the performance with the following machines..

    AMD Radeon HD 6770M with 512MB - 21.5"
    AMD Radeon HD 6770M with 512MB - 27"

    Of course i'd prefer a larger screen, but if it compromises the GPU performance then i'll stick with the 21.5" version (when Apple update).

    I've been lurking on this forum for a while, it's pretty funny watching people get depressed over a pathetic hardware update, people talk as if Apple owe it to them or something. Chill your beans!
  2. forty2j, Jul 24, 2012
    Last edited: Jul 24, 2012

    forty2j macrumors 68030


    Jul 11, 2008
    If you're truly interested in GPU performance, you shouldn't be looking at the 6770m models :eek:

    The 27" at native resolution has a lot more pixels to push around, and the 512MB 6770m chokes on it. By comparison, it merely struggles with the 1080p on the 21".

    Depending on your intended use, either might be just fine anyway.

    Edit: If you're waiting for an update, then the comparison isn't valid. A GTX 650M or 660M would perform pretty similarly at both resolutions.
  3. chris1987 thread starter macrumors member

    Oct 21, 2008
    I'm not looking to get a gaming setup, would just like the option to play some games every now and then.. ideally i'd like to see some FPS comparisons of games on the specs i just mentioned.. if it's a few FPS then i'll get the 27" model, if it's 15-20 FPS less then i'll stick with the 21.5" model.
  4. dearlaserworks macrumors regular

    Apr 28, 2012
    Eastern Shore, USA
    I'm not a gamer, but can't you run games in a 21" size window on the 27" display? I don't mean changing screen resolution, but I remember games back when running in a smaller window in the center of a bigger display. If so, then you could have the added workspace of the 27" as well as the gaming speed of a smaller screen.
  5. forty2j macrumors 68030


    Jul 11, 2008
    Finding benchmarks/reviews for 2560x1440 is very hard. Just about nobody but Apple runs mobile cards at that resolution.

    If you're interested in the 2011's, here's how the 6770m would fare on the 21": You could knock the 27" down to the same resolution for the same results; being a non-native resolution it's possible it might appear blurry to you. I can't find any numbers at all to show you for 1440p, but it'll probably feel 20-30% slower or choppier.
  6. theSeb macrumors 604


    Aug 10, 2010
    Poole, England
    You can basically forget about running games at 2560x1440 with that card, so even on the 27" iMac, you would have to run at 1920x1080 or even lower to be honest.
  7. iwb100 macrumors newbie

    Jul 18, 2012

    I'm not much of a gamer, nor an expert so can only go with personal experience since getting my 21.5" 2011 iMac last week with the 6770M in.

    Have played a few games on it under OS x. Handles them fine though not always at the highest details/resolution. Portal 2 with everything maxed out runs at 30fps and is absolutely playable, but thats portal 2....

    Deus Ex HR took some tweaking but at 720p with most things on medium settings get a very decent frame rate and it looks good to me, but again I mainly game on xbox 360 so....

    Serious Sam 3 medium settings and get a playable if not what (the pros would call playable) framerate of between 25 and 40 fps. Could turn things down lower if you demand 60fps.

    However, I understand you can use bootcamp and under windows the performance is better in general.

    For casual gaming like I do, then its fine. If you're wanting to play a large variety of games then bootcamp, if you're wanting the very top settings for the latest games then don't get the 6770m iMac....;)

    Would be interested to here what the gaming performance is like under ML and whether the GPU drivers are improved for gaming in OS x.
  8. leman macrumors G3

    Oct 14, 2008
    You should get the 6970M with the 27" iMac, its around 2x faster than the 6770M...

Share This Page