New iMac GPU performance

Discussion in 'iMac' started by any-key, Nov 23, 2012.

  1. macrumors member

    Joined:
    Sep 12, 2012
    #1
    I really looking to buy one of those new iMac's. At the moment I am using my MBA for serious work and I have a PC under my desk that I really only start up for playing games. I dont like the Windows PC sitting there unused except from gaming and I want to replace it with a gaming capable iMac.

    Now with the new iMac I am looking to buy either the 21,5" with GF GT 650M or the 27" version with the GTX 660M.

    The only thing that matters for me really is if the iMac GPUs will be capable of running my games in high detail. That is BF 3, Source games like Portal 2 and TF 2, Diablo 3 and StarCraft 2.

    I know its not fair to compare those mobile GPUs vs the Desktop (my PC has a Radeon HD 6870). I just wanted to know how much of a performance drop it will be compared to the Desktop and how do the GT 650M and GTX 660M compare?
     
  2. macrumors 68000

    azentropy

    Joined:
    Jul 19, 2002
    Location:
    Surprise
    #2
    Both "M" GPU's will be quite a bit slower than the HD6870. PassMark benchmarks I've seen have the 650M at about 1/2. The GTX 660M is about 20% faster than the 650M.

    http://www.videocardbenchmark.net/gpu_list.php

    http://www.videocardbenchmark.net/gpu.php?gpu=GeForce+GT+650M&id=122
    http://www.videocardbenchmark.net/gpu.php?gpu=GeForce+GTX+660M&id=1458
    http://www.videocardbenchmark.net/gpu.php?gpu=Radeon+HD+6870&id=22
     
  3. macrumors member

    Laucian Nailor

    Joined:
    Oct 24, 2012
    Location:
    UK
    #3
    Tom's Hardware graphics comparison will give you that (comparable performance though, not specific %'s):
    http://www.tomshardware.co.uk/gaming-graphics-card-review,review-32571-7.html
     
  4. macrumors 6502a

    luffytubby

    Joined:
    Jan 22, 2008
    #4
    BF3 will sing if you get the 27 Imac with the 680MX

    Trust me, running at 2560x1440 with everything on Ultra. It's very taxing. 660M is decent, but it seems redudant. Consider for a moment how expensive the Imac is. Go all in, or go for the 21 inch and forget about gaming IMO.
     
  5. macrumors member

    Joined:
    May 1, 2012
    #5
    I think it's an exaggeration implying that if you go for the 21.5" you'll be reduced to playing Angry Birds. My opinion is that the upper 21.5" will behave better in gaming than the lower 27". Why? Because the difference in the number of pixels is greater than the performance gap between GT650M and GT660M. For gaming I would stick with the upper 21.5", or if money is not an issue, go for the upper 27".
     
  6. thread starter macrumors member

    Joined:
    Sep 12, 2012
    #6
    Thanks. Thats really helpful.

    Yeah, I found that already. Unfortunately it doesnt really compare the GPUs side by side. So it doesnt give any hint on how far ahead the HD 6870 is vs the mobile ones.

    Thats what I was thinking too. Even though the maxed out is not exactly cheap :)
     
  7. macrumors member

    Joined:
    Apr 28, 2011
    Location:
    NJ
    #7
    If I remember correctly, the 6970m which was the top card of the 2011 models is just a down-clocked version of the 6870 desktop card you already have in your windows machine. The 650m is anywhere from on-par to 25-30% less than the 6970m. Therefore it would be reasonable to say that the 660m might perform about equivalent to the 6970m of last generation's iMacs. Just a thought, but worth pointing out, is that a refurbished 27" from the 2011 models might suit your needs better by giving you a higher speed processer and bigger screen for about the same money-wise. This would also allow you to upgrade the RAM yourself, something that you are incapable of in the 2012 21" models, as far as we know. The 675MX, and even better, the 680MX, are far superior cards to the 650 and 660m as has been pointed out. If you are concerned about gaming performance, I would bite the bullet and go for a top model at least and upgrade to 680MX if it's not too expensive. The performance will be at or above the level of the 6870 desktop card you have now. To help compensate for the additional cost, you could part-out your desktop or just offload it on the whole depending on the work you want to put in getting your money back.
     
  8. macrumors member

    Joined:
    Jun 17, 2012
    Location:
    Netherlands
    #8
    The 650M can play most of the newest 3D games in High settings with little issue. Disabling AA and decrease things like shadows a notch or two and you can play anything but Crysis 3 very nicely. However, don't expect these games can run like silk on Ultra, or if you turn on FPS killers like FSAA.

    650M can also play games with better frame rate at 1920*1080 on 21.5" compared to 660M at 2560*1440 on 27". Unfortunately you can't use 660M to 680MX on the 21.5", so if you want to get the best performance of all, in native resolution, you can only go 680MX on 27", which will cost you a ton of $$$.

    Whenever I see people discuss the 2012 iMac's GPU and speculated gaming performance, I'll doubly miss my old, sold GTX 560 T_T
     
  9. macrumors 6502

    Joined:
    Mar 28, 2011
    #9
    That assumes he boots using Bootcamp, correct?
     
  10. macrumors 6502a

    Joined:
    Mar 15, 2011
    #10
    I think you're off a bit. 660 is about 30% slower than the 6970m which is about equivalent to a 6850.
    680 MX should be quite a bit more powerful than the 6870.

    I think also an issue is VRAM. 512 MB is not enough for nice textures at 1080p.
     
  11. macrumors 6502a

    luffytubby

    Joined:
    Jan 22, 2008
    #11
    Yes. Parallels is a no go.

    BF3 varies a lot, depending on what you are doing. This is a trend we see more and more of in recent PC games. Guild Wars 2 is perhaps the most recent and most extreme examples.


    If you play Battlefield 3 on a 64-player servers, with the large scale maps. You must. You absolutely must play with a very good rig. But what an experience it is. If you have never seen it, you will be amazed. This sort of graphics is very close to what it would feel like to be in the middle of a Michael Bay action film. The scale and attention to details. The lighting alone becomes a big part of the gameplay.




    With an SSD the dual-boot process is so fast that you can get faster into Windows than it takes Steam on Mac to start. That isn't saying much considering Steam on Mac feels sluggish, but you get my drift:)
     

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