Is it my monitor or my video card?

Discussion in 'Mac Basics and Help' started by Luis Ortega, Sep 3, 2009.

  1. Luis Ortega macrumors 6502a

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    May 10, 2007
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    Fetcham Surrey UK
    #1
    Lately, I have noticed that my monitor screen suddenly goes into what looks like a tv set screen when there is no channel selected- what some people call snow on the screen. It's not a frozen pattern, and it is all over the screen.
    It has happened a few times in the past few weeks.
    Turning the monitor off and on immediately corrects the problem, and it doesn't happen again for days.
    Does this sound like it could be the monitor or the graphics card?
    Thanks for any advice.
     
  2. MTI macrumors 65816

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  3. Tomorrow macrumors 604

    Tomorrow

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    Always a day away
    #3
    Try hooking up a different monitor and see if the problem repeats itself - I suspect it's the monitor.
     
  4. Luis Ortega thread starter macrumors 6502a

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    Fetcham Surrey UK
    #4
    It's a Mac Pro and the monitor is a 23 inch Iiyama flat screen.
    Unfortunately, I have no other monitor to test, and the problem only occurs at most once a week since it started about 3 weeks ago.
     
  5. Tower-Union macrumors 6502

    Tower-Union

    Joined:
    May 6, 2009
    #5
    It COULD be artifacts from the graphics card, but given that its fixed by turning the monitor off and then on again I'd have to say its probably your monitor.
     
  6. velocityg4 macrumors 68040

    velocityg4

    Joined:
    Dec 19, 2004
    Location:
    Georgia
    #6
    I had this several months ago. With the same solution of turning the monitor off then back on.

    Fast forward two months and the video card died, problem found! Once I replaced the card everything has been fine.

    I would say your video card is starting to go as well.
     
  7. Luis Ortega thread starter macrumors 6502a

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    May 10, 2007
    Location:
    Fetcham Surrey UK
    #7

    I did replace the graphic card, an 8800gt, with a gtx250 recently, and it is such a beast that it was a bit hard seating it right.
    I tried to reseat it but the Mac Pro's PCI slots have a weird v-shaped clip at the back of the slot that needs to be pried apart a bit to loosen the card so it will come out.
    I am afraid to press it too far open in case it just snaps off, and the card is so big that I can't easily get my fingers to grasp the clip anymore now that it is installed.
    I was able to loosen the front part of the card (the side closest to the connectors for the monitor at the back of the case) from the PCI slot, but the back end where the clip is would not come out so I stopped trying to remove it and reseat it.
    I would like to be able to remove it completely, make sure the PCI slot is dust free and seat it again, but unless I find a way to access the clip on the PCI slot to pry it open a bit more, I won't run the risk of damaging it.

    I wonder if it isn't the monitor why just turning the monitor off and on immediately fixes the problem. If it was the graphics card, why should this affect it?
    I have seen faulty graphics cards and they seem to freeze and create weird patterns on the screen, but I have never seen this snow/white noise effect before. It looks just like a finer grained version of the static that you see on a tv screen when there is no channel selected.
     
  8. velocityg4 macrumors 68040

    velocityg4

    Joined:
    Dec 19, 2004
    Location:
    Georgia
    #8
    There problems are not always so pronounced at first. A lot of times problems start showing with many individual pixels being stuck it colors of Red, Green and Blue. Eventually you will start seeing much more pronounced artifacts on screen.

    As for removal. I don't the specifics of the Mac Pro's setup. But all the card lock I have seen have always been released by pulling out towards the side of the card with the GPU and heatsink. This has been the case with all 8x AGP and PCI-e x16 slots I have seen.

    Edit: You should only need to nudge the lock less then 1/2 and centimeter while pulling the card out.
     
  9. Luis Ortega thread starter macrumors 6502a

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    May 10, 2007
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    Fetcham Surrey UK
    #9
    I borrowed an older flat screen monitor from a friend and tried it on my computer, but it doesn't have the dvi connector, just a vga connector, so I had to change cables.
    My friend connected my monitor to his computer also using a vga cable since his video card only has vga connections.
    They were both fine, so I am starting to think that it might have been the dvi cable.
    Could a cable be the cause of the symptoms I described in the op?

    I then put my monitor back on my computer but I am using the monitor's vga connection instead of the dvi connection, using the vga to dvi adapter that came with the computer.
    So far it is behaving fine.
    If it remains stable for a few days, I will go back to the old dvi cable and see if the problem reappears.

    But if it is the monitor or my video card, would using the vga connection instead of the dvi connection mask the problem? Is there a signal difference between the two connection methods?
    That is, would sending the signal from my video card to a monitor through a vga connection make any difference if the video card had a fault? Would using my monitor's vga connection mask a monitor defect that is occurring when it receives the signal through its dvi port?

    Is there a qualitative or performance difference between using a dvi versus a vga connection from a computer to a monitor? If the monitor has dvi connections, will it perform worse if it is connected to a monitor with a vga adapter?

    I hope this makes sense.
     
  10. ukuleleman macrumors member

    Joined:
    Jul 19, 2009
    #10
    Duff video card

    I had exactly the same problem, wavy line patterns, very pretty but not helpful, gradually getting worse until I got to the stage where I had to boot up six or seven times to get a stable start up, but eventually it would be stable until the next boot up and then it all started again, same computer, Mac Pro. after a lot of thought and elimination I took the plunge and bought a new graphics card, my problems ended there.

    Don't know about the different cables so can't comment, but I strongly suspect that you will be laying out for a new card soon.
     

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