24" iMac with Spanned 23" ACD Performance

Discussion in 'iMac' started by Icewind, Jan 3, 2007.

  1. Icewind macrumors regular


    May 23, 2006
    Hey Guys,

    I've had a quick search of the threads but can't find any information that exactly relates to my question. Maybe someone will be able to answer this for me...

    I have a bog-standard 24" iMac C2D and have it hooked up to my 23" ACD (looks very cool by the way). However, I'm wondering if this setup actually decreases performance in anyway! I seem to be witnessing a bit of slowdown when I run applications, or when I drag windows about (like a stuttering in the movement). I'm positive this wasn't the case when I first got the iMac and didn't have the 23" ACD hooked up to it.

    Can anyone answer this from a technical perspective? Any advice would be greatly appreciated.

    Thanks.. and Happy New Year to you All.
  2. Killyp macrumors 68040


    Jun 14, 2006
    Why not just try un-plugging the ACD and see if it speeds back up? The problem might not be related to the fact that it's having to process more visually.

    It should be passing all that over to the graphics card, so programs should not open any slower. Anyway, the graphics card in any of the iMacs is more than enough to feed two monitors with hi-res OS X graphics...
  3. spork183 macrumors 6502a


    Jul 30, 2006
    umm, did you try disconnecting to see if the problem went away?

    Does "bog-standard" mean the 128mb graphics card? I can see that as a weakness if you're trying to power both monitors.
  4. Killyp macrumors 68040


    Jun 14, 2006
    No, the graphics card in the 24" is a very good chip (7300GT).

    128 mb doesn't refer to the power of the card, it is basically how many textures the card can show at once and call up quickly. The real figure of a graphics card is it's clock speed (although this is still highly variable).

    Either way, the 24" is definitely capable of driving two displays, both large...
  5. Icewind thread starter macrumors regular


    May 23, 2006
    Thanks for your quick replies guys.

    I have tried disconnecting the ACD, but it's quite difficult to tell if it's processing the graphics faster (mainly because I can only drag around windows on the iMac display and not drag them onto the ACD). I generally get the impression that it does run faster when the ACD is not connected. This is why I was asking if anyone could say from a technical perspective if the iMac's GPU would suffer a bit under the extra workload of having 2 displays to cope with.

    Yeah.. It's the 128Mb Nvidia 7300GT card installed in there.

    It's not crippling the iMac by any means, it's just I'm positive that there's a performance slowdown when the ACD is connected. But like I say, It's hard to tell when all my windows are on one screen. I'm sure it is a bit more 'sluggish' when spanned, but I'm ok with that, as the extra screen real-estate is well worth a small performance hit. It's brilliant not having to switch between overlapping windows to access apps, or information I need.

    I simply wondered if my thoughts were correct and that someone would be able to say "Yeah it will degrade gfx performance by x% due to blah" or something similar.
  6. eXan macrumors 601


    Jan 10, 2005
    It should not. The GeForce 7300 is strong enough to drive two big monitors at once.

    Some examples:

    My dad had 23" and 20" ACDs connected to his 1.8 dual G5 (with GeForce 5200) and there was no "sluggishness", now he has dual-core 2.3 G5 with 6600 and no slowdowns either.

    When I was in Apple Store (summer 2004 :D) I used a 12" PowerBook (GeForce 5200) with 23" ACD connected to it in the screen-spanning mode, there were no slowdowns.

    7300 is much more powerful than 5200, so it should not be worse in driving two big monitors at once.

    If dragging the windows seems "choppy" try restarting and see if it is better. I had this issue a while ago (and im runnning a since 17" screen :eek: !)
  7. 3CCD macrumors member


    Jun 30, 2006
    FL and NJ
    Intresting, I'll be getting a free apple monitor from my brother thats only 17" (the older Apple flat screens) to go with my 24" iMac. Can't wait.
  8. pseudobrit macrumors 68040


    Jul 23, 2002
    Jobs' Spare Liver Jar
    I've heard anecdotal reports of choppy performance from spanned iMacs.

    I'd like to know how the 24" iMac does with the 7600 spanning to another WUXGA display.
  9. iW00t macrumors 68040


    Nov 7, 2006
    Defenders of Apple Guild
    I can't believe what I am reading. Even the 7600GT is considered a budget chip nowadays, the 7300GT is basically the cheapest chip in the current 7XXX line. Is it just me or do Mac users have extremely low standards?

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