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I have a Dell Optiplex 780 computer (using a AMD Radeon 3450 if that helps), which I connect to my monitor with a DMS-59 splitter, to split it into 2 VGA cables.

When booting into BIOS, both monitors display the BIOS screen, and even the windows (7) loading screen is shown on both monitors, however, when windows actually loads up, one of my screens does not show an image, just a black screen.

Both screens are usable when used as just a single screen, it is just when trying to set up dual screen that I have run into this issue.

Can anybody help me work out how to make my second screen usable in Windows?

Thank you very much

2 Answers 2

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I'm assuming you've already tried going into AMD Catalyst Control Center and (separately) Windows' own screen properties (right click the desktop) and trying to enable both monitors?

If this is a NEW problem (you've gotten this to work before with the exact same hardware)

  • Try updating your drivers. Note that you are using an End-of-Life unsupported video card which is not receiving regular driver updates from AMD anymore, so if it is a driver problem, there is very little hope that a fix will ever arrive.

  • Try reinstalling Windows, or at least boot up a Live CD/DVD of Ubuntu or Fedora and see if that can detect and initialize both monitors.

If you've never gotten dual monitor to work before

  • It could be that the total resolution of both your monitors (add up the vertical and horizontal) may be greater than the supported framebuffer size of your GPU. Considering how ancient your GPU is, this isn't very hard to imagine being the case. I was only able to find one anecdotal site after many minutes of googling showing that the maximum resolution is possibly 2560x1600. If you're trying to connect two 1080p displays (1920x1080), then 1920*2 = 3840 and 1080 * 2 = 2160, both of which are greater than the maximum respective WxH components of 2560 and 1600.

  • It could be that the driver support is not there. Again, trying to update to the latest supported driver or running Ubuntu to see if it also breaks there might provide more info.

It seems like you're not the only one with this question, either.

The only real solution I can think of is to use an actually modern GPU.

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  • You were correct about the resolution being too high, however, lowering it did not fix the issue. I think you may be correct about the gpu being too old - I had hoped this wouldn't be an issue when I bought the computer, however it should not be too much of a problem to upgrade it to something slightly more modern.
    – Jon
    Sep 2, 2014 at 19:20
  • There are good and modern GPUs available in the $100 price range. Something like an R7 265 or R7 260. Sep 2, 2014 at 20:20
  • How about something like a Nvidia 610? I'm not planning on using this for gaming, so would this be a possible choice?
    – Jon
    Sep 4, 2014 at 18:30
  • I don't know about the Nvidia 610, but if it has two ports of the type you need, it should work (no promises though; I haven't researched that card!) Sep 4, 2014 at 19:44
  • Ok, that's fine, thank you for all your help, you've been really helpful :-)
    – Jon
    Sep 4, 2014 at 19:56
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You would require at least two separate physical ports on your graphics card for a dual monitor setup. The Os has no way of identifying two separate monitors with a basic splitter.

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