Clamshell Mode - Performance Hit?

Discussion in 'MacBook Pro' started by Kibbles, Oct 22, 2008.

  1. Kibbles macrumors newbie

    Oct 22, 2008
    Hi all. Will I see a performance hit (in Games, more specifically) if I run an external display and the built-in display at the same time?

    If so, would running in clamshell mode resolve it?
  2. Michael CM1 macrumors 603

    Feb 4, 2008
    I would expect a hit since you're putting stuff on two displays instead of one. I'm not exactly sure what game there is that you need two displays for (WoW works fine on a 20"), but I'm guessing it could be done.

    You shouldn't have any clamshell issues if you make sure everything is properly ventilated. I recommend finding a USB fan to sit underneath the MBP. That should make up for the lost ventilation that comes through the keyboard.
  3. Kibbles thread starter macrumors newbie

    Oct 22, 2008
    I mean playing a game on one display, the other displaying something static or idling.
  4. sfroom macrumors regular

    Apr 30, 2008
    Depends what you're using the computer for.

    Running two displays will use more of the video card's memory. This shouldn't be an issue for gaming. There should be plenty of memory to run the internal display and a 24" (1920x1200) external display. A 30" might be pushing it, and if you're gaming at native res. on a display that large, I expect you'd most definitely see a performance hit.

    My opinion is that with something relatively idle on the secondary display, the video performance hit while gaming should be minor with an external display 1920x1200 or smaller.

    If you're doing something like rendering, on the other hand, where your video memory might be pushed to the max, you'd definitely see a performance hit.
  5. DoFoT9 macrumors P6


    Jun 11, 2007
    if i am not mistaken... if you have two monitors the RAM usages is split between the two, so performance may take a hit.

    if you are going to be gaming on one screen and looking at your emails, web, itunes etc on the other then there will be minimal impacts.

    however, if you are going to be gaming on one screen and doing something GPU intensive in the background on the other screen the performance may take a very big hit!
  6. Michael CM1 macrumors 603

    Feb 4, 2008
    I might find out which MBP he has before claiming said GPU can handle all of that. My GPU is the ATI 1200, and it's decent but not spectacular when I run WoW. Often, I can't get much better than 20 fps on a 1680x1050 display.

    But if he's got the new MBP, he should be set.
  7. sfroom macrumors regular

    Apr 30, 2008
    I assumed he had a MBP purchased in the last year, and I guess I should clarify that I based my advice on the assumption that the OP had a video card with at least 256 MB of video ram.

    Running an external 24" display in addition to the internal display with only 128 MB of video memory would probably cause a noticeable performance hit.

    That being said, I used to run an external display (22" 1600x1050) with my 24" white iMac with a 256 mb 7600 GT. I used the second display for Ventrillo/Teamspeak, Thottbot/WoWwiki/Wowhead, etc., and the performance hit was not particularly noticeable.

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