DVI-D projector image problems

Discussion in 'Computer Components' started by mark05, Jan 29, 2009.

  1. mark05

    Standard Member

    Jan 12, 2006
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    Hi All,

    I'm having some trouble with DVI image quality on a dual head graphics card:

    I have a PC with monitor and projector, I want to have a cloned desktop setup with the VGA output to the monitor and the DVI to the projector.
    As all this is installed in a lecture theatre at work I tested things first with a short DVI-D cable and all was fine, but when I got a longer (3m) DVI cable things all went horribly wrong: The image on the projector is garbled unless I set the aspect ratio to letterbox (needs to be wide for 1280x768), then it is all squashed and loses the top and bottom of the image!

    Things I have tried so far:
    1.5m DVI-D cable and cloned desktop - good picture
    3m DVI-D cable and extended desktop - good picture
    3m DVI-D cable and cloned desktop - garbled picture

    The reason I'm doing this is because we are currently using the VGA input on the projector through a splitter and VGA switch to provide for laptops, doing this we get shadowing even bypassing all the switches - text looks smudged.

    I'm not sure how long the cable is to the projector, I'd guess it could be up to about 6 or 7 metres, so plus the cable to the PC it could be 10m.

    Has anyone got any idea why this is all going so horribly wrong or what I could try instead?

    I need to get a good image on the projector primarily, with facility to plug in a laptop too.

    Thank you


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