iMac external monitors, dual splitting w/ mirroring

Discussion in 'Mac Accessories' started by noahsnyc, Jul 2, 2010.

  1. noahsnyc macrumors regular

    Sep 27, 2003
    Los Angeles
    I've been in and out of this forum for the better part of the day trying to figure out my scheme for a dual-monitor/TV mirroring plan.

    I've got an iMac and currently have it DVI-out-to-HDMI to my television.

    What I'd like is to use a DVI-splitter to a larger monitor for my main monitor and when I turn on the television, have that mirror the external monitor as well.

    So, it'd look something like this:

    iMac (SECONDARY MONITOR) out to a DVI splitter =

    1) External DVI monitor (PRIMARY) - Always on

    2) External television (PRIMARY MIRRORED) - Sometimes on

    My main question is: If my external monitor is a lower resolution than my giant television, and both are set to be primary (because of the splitter), how is resolution determined?

    Thanks in advance,
  2. carlosbutler macrumors 6502a


    Feb 24, 2008
    London City
    I believe you will only be able to select one resolution, as there is only one output. You will therefore need to have the monitor at 1920x1080 (the TV res) which is very wide and not very tall respective of a computer monitor:

    (1920/1080)*9 = 16 => (implies) 16:9 ratio ('full' HD TV)
    (1920/1200)*10 = 16 => 16:10 ratio (~60-70cm monitor)

    But it will work nonetheless
  3. noahsnyc thread starter macrumors regular

    Sep 27, 2003
    Los Angeles
    I think you're absolutely right. The iMac will only recognize one resolution. So what does the iMac do if it's connected to a 1920x1080 monitor AND a lower-resolution monitor via the same connection (DVI splitter)?

    Keep in mind, only on rare occasions will both monitors be ON, although they'll always be connected via the splitter.


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