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currently in my XP machine I have one video card with one VGA output. With that VGA output I am using a VGA splitter and connecting two monitors. XP Detects the second monitor and lets me do the usual functions on it. If I go to display properties I can see two monitors labelled "1" and "2".

Now when I run the same setup (different vid card, maybe newer I dont know) Win 7 only detects one monitor. My internet research showed me that it is impossible to have two monitors detected by the OS when using a VGA Splitter. I must either use a video card with two outputs or use some other similar device.

My question is how can XP detect two monitors but Windows 7 cant?

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What is the model number of the video card? –  Cameron Aziz Jul 4 '12 at 20:05
    
Also what kind of splitter do you have? –  imtheman Jul 4 '12 at 20:55
    
Simple terminology query: SPLITTER? That usually is a device that takes one input, and duplicates on ALL its outputs. It will not 'add' a second monitor with a separate image, but it will add a second monitor with a DUPLICATE image. If it really is a 'splitter', then Win7 is correct, you only have ONE output. No idea why WinXP is confused. –  lornix Jul 6 '12 at 5:55
    
I am going to take a jab at this question. It sounds like the video card in the Windows XP machine actually supports having an output to multiple monitors. The video card in the Windows 7 machine does not. Unless you provide information on what EXACT video cards you are using we cannot help. –  Ramhound Aug 27 '12 at 15:38
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2 Answers 2

There is a type of VGA y-cable that allows driving two separate monitors from a single card, with a single VGA port, but I've only seen them in Dell branded machines here at work. Likely Dell had to write a special driver for XP to support this functionality, and they haven't ported the driver to Windows 7, and so it's defaulting to standard VGA address-ability, because of performance limitations of their interface, vs the more modern HDMI standard.

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Splitters don't support extended desktop applications. All a Video Splitter does is display the same image on multiple monitors. If you are looking for extended desktop features you probably need a video card with multiple video outputs.

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