Odd Screen issue after hooking up to projector

Discussion in 'MacBook Air' started by treehorn, Apr 29, 2015.

  1. treehorn macrumors 6502


    Aug 21, 2007
    I have a really weird occurrence that happened whenever I hook up my computer to a projector via a VGA Adaptor. The computer will work fine until it gets hooked up, at which point upon startup I get a quick flash of bands of 'visual noise' on the startup screen (after the Apple appears).

    The weirdness is that this flash of noise will happen constantly after that point whenever I start up the computer and sometimes when I shut down.

    If I zap the PRAM, this will stop. But as soon as I hook it up to a projector it starts happening again (and it doesn't matter the make or model of projector - this happens whenever and wherever I do this, even using ones on the road provided by other schools/companies).

    While I can zap the PRAM after each time I use a projector (which is daily), I want to make sure that there isn't any underlying issue with a graphics card, the video output portion of the computer...a software glitch (as an aside, I got the computer right before having to spend a month in China and the first projector I used was there...could that have caused any problem? Just ruling out all possibilities)

    When I took it to TechServe they suggested the PRAM zap, which worked (until I started using a projector again). I've included a pic of the noise for reference. thanks!

  2. b06tmm, Apr 29, 2015
    Last edited: Apr 29, 2015

    b06tmm macrumors regular


    Jul 23, 2009
    South Louisiana
    You don't mention the type of computer you are using.

    If it's a rMBP and it has an integrated and a discrete graphics adapter you can download gfxCardStatus.

    This will allow you switch graphics adapters on the fly to see if the issue is with one of the graphics adapters.

    I just realized you posted the MBA sub-forum, so you have no discrete graphics adapter.
  3. motrek macrumors 68020

    Sep 14, 2012
    Wait, so the problem is that you get a brief flash of noise on the screen when it doesn't matter at all what's being displayed on the screen (because the computer is booting up or shutting down)?

    I must be misunderstanding something.
  4. treehorn thread starter macrumors 6502


    Aug 21, 2007
    Well maybe not misunderstanding but being awfully dismissive of something.

    As this is not a normal occurance, and as things that aren't a normal occurance should usually be looked into to make sure it doesn't signify a deeper issue (graphics card problem, memory problem, etc) that should be repaired, or a hiccup that can indicate a software glitch...forgive me for asking if it's something anybody else has come across
  5. motrek macrumors 68020

    Sep 14, 2012
    Sorry for being dismissive.

    The issue is that a computer is not a mechanical device like a car. With a car, of course you should investigate any unusual noise or vibration, because it indicates something is probably wrong, and that something will probably get progressively worse until there's a catastrophic failure.

    This idea doesn't apply to computer since it's fundamentally different technology.

    If you are able to use your computer without glitches for any significant amount of time, basically everything has to be working 100% perfectly, so, no need to worry.

    If I had to guess, the problem has to do with negotiating a resolution with the projector. Back in the olden days of CRT monitors (~12 years ago) the monitor would do all sorts of disconcerting stuff when a resolution was being negotiated, like pop and flash and distort. Since you are using an old school analog connection I suspect the same thing is happening but with modern digital projectors all this popping and flashing manifests itself as some random digital screen noise.

Share This Page