rMBP GPU performance with external display

Discussion in 'MacBook Pro' started by Forerunner, Dec 27, 2012.

  1. Forerunner macrumors member

    Joined:
    Dec 24, 2012
    Location:
    California
    #1
    Hi all,

    The GPUs in both the 13" and 15" rMBPs are barely enough (if enough at all) to handle the higher resolutions of the Retina displays. My question is: how do the rMBPs perform when connected to external displays but with the laptop still open and functioning as a second display.

    Will I experience a significant decrease in graphics performance? Lag? Sluggishness?

    Any input/experiences would be greatly appreciated. Don't say "well, try it out for yourself and see... if that was an option, I would have already done it."

    Thanks in advance,
    Forerunner
     
  2. leman macrumors 604

    Joined:
    Oct 14, 2008
    #2

    What kind of 'performance' are you talking about? Playing demanding games on multiple monitors or just the usual desktop stuff? For desktop UI performance, there should be no perceivable difference with an external monitor, unless you are using some very demanding/badly written applications.
     
  3. Barna Biro macrumors 6502a

    Barna Biro

    Joined:
    Sep 25, 2011
    Location:
    Luzern, Switzerland
    #3
    The "GPUs are barely enough" is just garbage that you have most likely picked up from the posts of the masses of incompetent morons who believe they know anything about hardware or software... The GPU is more than fine, same for the CPU. What Apple needs to optimize are the scaling and rendering algorithms implemented by the OS ( of course they could just add more raw power to mask the inefficient stuff they have going on there - which would still overall suck ).

    That being said, both models can push pixels on external monitors just fine ( even on 2 monitors at a time ). As for gaming... that's a totally different topic. You can surely play the same games you play on the notebook while connected to an external monitor as long as you don't expect ( for whatever reason ) the games to suddenly perform 2-3 times better than they were already doing on the notebook and as long as you keep the graphical settings unchanged / very similar.
     
  4. sireShonBohn macrumors regular

    Joined:
    Jun 18, 2012
    #4
    There's no difference really. The one thing to note is that the rMBP will default to high performance mode with an external monitor attached. This is the same as disabling "Automatic Graphics Switching" in the Energy settings. Due to this one may find that the UI stuff runs better with a second monitor attached...
     
  5. Forerunner thread starter macrumors member

    Joined:
    Dec 24, 2012
    Location:
    California
    #5
    You are right about the scaling algorithms. But that doesn't negate the fact that given the current software of the rMBP, the GPU is not powerful enough to overcome the sluggishness of the inefficient scaling/rendering.

    I know the laptop can power two 27" Thunderbolt displays, but my real question here is how well it can do so. The fact that my laptop will not be in clamshell mode means that a significant amount of resources will be dedicated to the smaller of the displays.

    I apologize for the lack of clarity. My question is geared towards regular day-to-day OS usage. I have no expectations for a smooth gaming experience.
     
  6. Barna Biro macrumors 6502a

    Barna Biro

    Joined:
    Sep 25, 2011
    Location:
    Luzern, Switzerland
    #6
    Ehm, no... Sorry, but I can't agree with you. The 15" rMBP with forced dGPU can also produce stuttering / sluggishness while fast scrolling and fast screen / application switching ( not to mention it has a quad-core CPU compared to the dual-core of the 13" rMBP ). It's stuttering because they simply tried an approach that was never widely tested before ( this whole constant scaling / rendering combo ) and since they couldn't make it perfect / mega-optimized from the very beginning, it will clearly take some time until they get it right. The "add more juice" barbaric approach is completely unfeasible ( would you really pay 1.5x the money - or more - for an even beefier notebook just so that it can handle the UI / scrolling without stuttering? Most likely not... ).

    As for the "how well will the notebook handle the external display": it would be wonderful if you would maybe first tell us "what you're planning on doing on those external screens". Normal / simple tasks for sure it can handle fine ( no noticeable difference compared to how things run on the integrated display ).
     
  7. leman macrumors 604

    Joined:
    Oct 14, 2008
    #7
    Its hardly the fault of the hardware if an application does not use the API in an optimal way. Sure, some of the Apple-provided software could be better optimised. The way App Store or Mail handle resizes is particularly bad, and Safari is still crap overall. However, Calendar's/iTune's UI is every bit as complex as that of Mail, and they handles resizing smoothly. And latest WebKit builds are able to render even the most complex of websites without any problems. The difference is really just the skill of the programmer.
     
  8. lightz39 macrumors regular

    Joined:
    Nov 30, 2012
    #8
    You'd figure it would work better, at least if your laptop is closed. You'd be rendering in 1920x1080 vs 2880x1800. That is much fewer pixels.
     
  9. Ploki macrumors 68000

    Joined:
    Jan 21, 2008
    #9
    OP was asking about 2880*1800 AND 1920*1080.
    I would also like to know whats with or/or.
     

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