dvi>vga adapters

Discussion in 'MacBook Pro' started by nyutnyut, Dec 4, 2008.

  1. nyutnyut macrumors member

    Joined:
    May 22, 2008
    #1
    so i'm finally getting a MBP (hopefully tomorrow!) to replace my G5 desktop.

    I have a 22" LCD external monitor, and i also have a KTM swith made for VGA connections. since DVI KTM's seem to be $100+ i want to use the old KTM switch for my desktop and MBP. I have the DVI to VGA adapter from my old ibook and will have another one from my MBP. just need the adapter to the monitor.

    will using the DVI to VGA adapters on all DVI connections do anything to the resolution on the external?

    seems weird to do, but I don't really want to drop any more money after paying for the computer, 4gb of ram and a laptop cooler.
     
  2. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #2
    Assuming your 22" LCD isn't an Apple, and therefore has a native VGA port; you'll be fine. You may have to mess with the various 'tracking' controls to get the picture nice, but you should be able to do full resolution.
     
  3. nyutnyut thread starter macrumors member

    Joined:
    May 22, 2008
    #3
    it's an Acer with a dvi port. so that would require an adapter as well.

    oh i should probably state that the MBP i got is a last gen 2.4 ghz. so not a mini-dvi port

    thanks for your response!
     
  4. Anonymous Freak macrumors 601

    Anonymous Freak

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    #4
    If the monitor *only* has a DVI port, then check its manual. Apple's DVI-only monitors are digital-only; so you have to have a DVI KVM switch.

    Summary: DVI is a physical plug. There are three standards:
    DVI-I is a plug that can carry either an analog signal or a digital signal. Nearly all video cards that are DVI are this variety. This can be converted to VGA with a simple plug adapter, since the port carries a standard VGA signal as its analog component.
    DVI-D is a plug that *ONLY* carries the digital signal. Most DVI ports on monitors are this variety. Apple's monitors only have this connection, therefore they cannot be adapted to VGA at all.
    DVI-A is an almost-never used analog-only version of DVI. When the DVI spec was first made, it was assumed that the DVI plug would completely replace the VGA plug, so CRTs would use DVI-A. That didn't happen.

    The easy (but not 100% accurate,) way of telling which one your monitor has is to look at the port on the monitor. There is the big bunch of pinholes, then off to the side is a 'tab'. If this tab has four pinholes around it, then it can take the analog signal. (Those four pins are part of the analog spec. Digital-only connections are missing those four pins.) See the Wikipedia article, look at the picture of the different plugs about halfway down on the left, you'll see that "DVI-D (Single Link)" and "DVI-D (Dual Link)" are missing those four pins around the tab.

    If your monitor says it is DVI-I, then an adaptor would work on it. If your monitor says it is DVI-D, or if those four pinholes are absent, then you will need a DVI KVM.

    Edit: The lack of the four pins around the tab is not a guarantee that the monitor supports analog. Some manufacturers are lazy and use the one plug on everything. Read the manual to be sure.
     
  5. nyutnyut thread starter macrumors member

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    May 22, 2008
    #5
    thank you very much. you have been extremely helpful.
     
  6. nyutnyut thread starter macrumors member

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    May 22, 2008
    #6
    damn, looks like the monitor is DVI-D. sucks the DVI-D KVM switch is $100 more then the VGA i bought a couple years ago.

    oh well, thanks again.
     
  7. Anonymous Freak macrumors 601

    Anonymous Freak

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    #7
    Yup. I've been putting off a DVI KVM for some time; and making due with an ancient VGA monitor on one computer for that very reason.
     

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