Second Monitor Flicks on and off

By Satki ยท 9 replies
Sep 1, 2009
  1. I have attached a second monitor to my laptop (DELL 9400 - using a geforce go7900gs) via the VGA cable on the back.

    The monitor worked fine for a few days, and then, after I came back from being away away over the weekend, I'm now having trouble with the display on the second monitor (the laptop display works fine). The second monitor will only display the screen for about 1/2 a second, then becomes blank for 5 to 10 seconds before reappearing for another 1/2 second. I don't think that the monitor loses the connection (when it does a box appears on screen saying that the signal has been lost).

    I'm 99% sure that the problem is not in the monitor or the cables, as I have attached my 360 to the monitor via the same VGA input as well as a seperate laptop with the same cable and these both function correctly.

    I'm guessing that the cables at the back were pulled down somehow and damaged the VGA output on the laptop, and if this is the case, has anyone else had this problem and managed to find a fix?

    The laptop also has a DVI output, and I have a DVI - VGA apaptor, but I can't seem to get an image to appear on screen via this route. Is there a video card setting needed to turn the DVI output on?

    Thanks for your help

    PS. First Forum post, don't flame the noob :p
  2. raybay

    raybay TS Evangelist Posts: 7,241   +10

    Be sure you have all the Dell updates downloaded from the Dell site for the 9400.
  3. Satki

    Satki TS Member Topic Starter Posts: 24

    Thanks for the reply,

    Like I said, it worked fine for a few days, and I havent made any driver changes since then, so I don't think that would be the issue.

    On a related note, do you think that Rivatuner could be causing this?
  4. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,742   +421

    I've had that happen with my 8800GTS on 2 Benq 20.1" monitors, with only the right monitor doing that. Its just poor drivers by nvidia. You can fix it by going into the display properties, changing which is default monitor (or changing resolution) and then changing it back. It will then work fine for a while.
  5. Satki

    Satki TS Member Topic Starter Posts: 24

    Tried that, at a lower resolution, the screen pops up more frequently and for a bit longer, but its still not really useable.

    UPDATE: I tried a system restore to when the monitor was working perfectly (back about 3 or 4 windows updates), now nothing will transmit to the monitor, and I'm getting a adobe related crash that for some reason causes explorer to crash whenever I right click or use macros (it might be a virus, though I don't see how it would have got on there), or else something got corrupted on restore.

    I'm probably going to end up formatting the hdd and reinstalling windows tonight... fun times
  6. Satki

    Satki TS Member Topic Starter Posts: 24

    Done a Reformat/reinstall of windows, and still no display, so neither the software nor the monitor is the problem... the only thing that I think it could be is the VGA port on the laptop, which I have no idea if it is even possible to repair... Does anyone know if its part of the mobo or the graphics card on the dell inspiron 9400?
  7. raybay

    raybay TS Evangelist Posts: 7,241   +10

    It sounds as if you are trying to run both video graphics outputs at the same time. Right?... not switching from one to the other.
    From what I remember, you have not yet told us the brand and model of the monitor(s) you are using.
    But the problem is more common than you may think on a great number of laptops.
    Your 6400 came out in about June or July of 2006... so it is three years old? Right?
    It is a driver and a laptop power issue on the older Dell, HP, and Sony laptops.
    The second port was not placed with the intention to run graphics signal to two monitors at the same time. Your 6400 is getting long in the tooth.
    The port on the laptop was to run another monitor INSTEAD of the laptop screen... for testing and receiving signals for processing. You may have overdriven the video graphics system to harm the Dell Intel, ATI, or nVidia video hardware ( I don't remember which you have on your 6400) but the issues will be similar whether you have the Intel onboard, ATI Radeon, or the nVidia GeForce Go 7300... with all the other gadgets that were available when that laptop was issued..
  8. Satki

    Satki TS Member Topic Starter Posts: 24

    Thanks for your reply

    The laptop is a Dell inspiron 9400 with a single VGA output and a DVI-D output (not used)
    The external monitor is a LG Flatron W2243S (1920x1080 22") with a single VGA input, the problem does not lie with this monitor (it runs perfectly well with other laptops and a 360)
    The laptop monitor is the standard dell supplied 1440x900 17" monitor
    I was trying to run them simultaneously, but the external monitor won't show anything on screen now.
    The laptop is about 3 years old and it uses the NVidia geforce go 7900gs (256mb)

    I really don't think that the card has burnt out, as it was only used for probably a maximum of about 10 hours total before the problem occurred, and the majority of that was in the desktop. It's also functioning as well as it ever did in games on the laptop screen (no drop in FPS since running the second monitor).
  9. raybay

    raybay TS Evangelist Posts: 7,241   +10

    I believe that is is the running them simultaneously that is the problem. Don't both work when run alone?
  10. Satki

    Satki TS Member Topic Starter Posts: 24

    Nope, laptop screen works fine in laptop only and clone/independant desktop modes with two monitors, but the external will not show anything on clone/extended desktop or external only.
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