Monitor flicker & electromagnetic interference
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Thread: Monitor flicker & electromagnetic interference

  1. #1
    Join Date
    Dec 2001
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    Colchester,Essex,England
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    Monitor flicker & electromagnetic interference

    Hello!!

    I have just moved our office computers to a new premises and we have gained this rather frustrating problem.

    In the old office the monitors were fine, no problems. Now, all the monitors flicker continously (to differing extents). The problem IS NOT software related, as they were all working fine before the move. Ive seen the exact flicker before when a speaker gets to close to a monitor. However, this flicker seems to be caused by some larger source, as when i move monitors around the flicker remains.

    Most interestingly, the flicker seems to be milder when the refresh rate is higher, and at >85hz the flicker is 'bareable'. Of course, only a few of our systems are capable of 85hz. It seems that the closer to 60hz the refresh rate of the monitor, the worse the flickering is (maybe because the interfernce is electrical).

    I have been told that it could be caused by things such as mobile phone transmitters (of which one is nearby, but no closer than in our old office) or railways (we are not near one of those).

    I am most interested in somthing that could tell me where the interfencing is localised (a kind of detector device).

    Any idea, thoughts or insults welcome.
    just dont tell me to download the latest graphics driver

    Thanks

    ------------------
    --
    Sigs are for twats
    Sigs are for twats

  2. #2
    Join Date
    Apr 2000
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    UK
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    8,466
    You are a gibbon.

    MuFu.

    P.S. Welcome to HWC. I can only offer an insult. I'm sure someone else can help you.

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    More # please...
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  3. #3
    Join Date
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    Oh... just had a thought as well. It could definitely be to do with the power supply for your office. Dodgy PSU's sometimes cause monitor flickering so I guess a dodgy mains supply could do the same if it isn't regulated.

    All I need now is an idea and then I would have provided all three. I have no idea, LOL.

    MuFu.



    ------------------
    More # please...
    Opteron 144@2.8GHz (stock HS/fan), Asus A8N-SLI SE (passive NB), 1.5GB RAM (2:3:2:5, 2T), WD Raptor 740GD 74GB, Maxtor DM10 300GB, Asus EN7600GT SILENT@???, M-Audio Revo 7.1, Nebula DigiTV, Dell 2005FPW, Enermax 431W Active.

  4. #4
    Join Date
    Dec 2001
    Location
    Colchester,Essex,England
    Posts
    3
    >P.S. Welcome to HWC..

    Cheers!

    >It could definitely be to do with the power supply for your office.

    I see. I guess i can run one of the monitors through the UPS to see if that clears it up. If so, i'll have to get a fatter UPS that can run all the monitors, or investigate fixing the main supply.

    ------------------
    Sigs are for twats
    Sigs are for twats

  5. #5
    Join Date
    Apr 2000
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    UK
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    A problem like this could also be caused by having your monitor in front of bundle of mains wires in a wall, or having it near a transformer. Thoses seem unlikely though from what you have said.

    Do you have a low ceiling with fluorescent lighting? That'd screw things up. Not by much though. Maybe you'll have to work in darkness.

    MuFu.

    P.S. Quite a lot of office units have dodgy power supplies. It's because they are built with a Power Factor in mind (the rating by which electricity companies charge you - the phases of either the voltage or current of a mains supply are messed around to minimize this, sometimes causing problems).

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    More # please...

    [This message has been edited by Mutha Funker (edited 12-13-2001).]
    Opteron 144@2.8GHz (stock HS/fan), Asus A8N-SLI SE (passive NB), 1.5GB RAM (2:3:2:5, 2T), WD Raptor 740GD 74GB, Maxtor DM10 300GB, Asus EN7600GT SILENT@???, M-Audio Revo 7.1, Nebula DigiTV, Dell 2005FPW, Enermax 431W Active.

  6. #6
    Join Date
    Mar 2000
    Posts
    27,205
    Originally posted by gibber:
    ... the flicker seems to be milder when the refresh rate is higher, and at >85hz the flicker is 'bareable'. Of course, only a few of our systems are capable of 85hz. It seems that the closer to 60hz the refresh rate of the monitor, the worse the flickering is...
    It's the fluorescent lights combined with low refresh rates of the monitor.

    From c|net,

    ...A refresh rate of 60 Hz (in which the screen is redrawn 60 times per second) will almost always look flickery--especially under fluorescent lights, which refresh at about the same rate. This causes eye fatigue. Refresh rates of 70 Hz and higher are preferable. Since refresh rates can vary depending on the screen resolution you pick, check that both the monitor and display adapter you run can manage a 70-Hz or higher refresh rate. ...


    Time for new monitors and/or video cards.


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    "I know nothing."
    Cheers.
    "I know nothing."
    Cheers.

  7. #7
    Join Date
    Dec 2001
    Location
    Colchester,Essex,England
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    3
    >Do you have a low ceiling with fluorescent lighting? That'd screw things up. Not by much though. Maybe you'll have to work in darkness.

    Yes, we do, but i the dark the problem is no better. Today im gonna drag a power extension from the old office (about 100 yards away to test the mains supply.

    ------------------
    Sigs are for twats
    Sigs are for twats

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