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I have a laptop with a USB to VGA adapter which allows me to add a third monitor to my laptop (the second monitor uses the onboard slot).

It worked fine on Windows Vista - you could go into Windows' display settings and Windows would recognize the third monitor and let you drag it around accordingly. With Windows 7, the third monitor literally is not there in Windows' display settings. The driver allows you to display to the third monitor, but you can't move where it is. The display settings are misplaced relative to my other two (if you drag windows over to it, they end up on the bottom when it should be aligned).

I called tech support and they said that there isn't a driver with this functionality for Windows 7 yet. But here's my hunch. The monitor placement is still somewhat similar to where I had it on Vista, it's just off about 500 pixels or so. I think there is either a registry key or driver file somewhere that is telling this monitor where to exist. If I could just modify the number and move it up 500 pixels, it would be in the right place and I don't have to wait 6 months for the company to come out with a new driver.

Any ideas?

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3 Answers

up vote 1 down vote accepted

Check out the various keys and folders in

HKEY_CURRENT_CONFIG\System\CurrentControlSet\Control\Video

Specifically in the innermost MonXXXXXXX sub-folders should be Attach.RelativeX and Attach.RelativeY values which are the monitors' location in relation to pixel 0,0.

Strangely when I check a Windows 7 machine here with two monitors, it doesn't seem to show the second monitor. But my XP machine shows all three of mine, so your mileage may vary.

If nothing else it's a place to start!

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Great find! This is exactly they keys I was looking for. Modifying the relativeY value in two places and then restarting the extended desktop usb driver causes it to shift. Now here's the remaining problem: Because of the way the monitors are configured, I need to put in a NEGATIVE value. How would I do that? Putting in a positive value only puts the monitor I need even lower. Here is my setup: 2 3 1 Those are the monitor numbers (1 and 2 are touching and three is off to the side). Changing the attach.relativeY value makes 3 appear to go even lower, I want to raise it. – dfree Feb 9 '10 at 21:45
looks like the formatting didn't keep there but hopefully you get the gist - 2 is above 1 and three is on the right of both of them, centered in between the two. Digitally, windows is placing it next to monitor 1. – dfree Feb 9 '10 at 21:47
Waht happens when you try entering a negative value? In the end, you may have to rig a startup script to make the adjustment when you log in (if it's not going to stick on it's own). – techie007 Feb 10 '10 at 4:56
You can't enter a negative value, windows won't let you. In the hexidecimal part of the registry you can put numbers and letters and in the decimal portion you can only put numerical values. That 4 billion number I posted definitely works and sticks, I'm just not sure why. Maybe there is some sort of code in windows that means that the 429496xxxx denotes a negative number. The last 4 numbers correlate to the amount of pixel deslpacement beyond the negative. – dfree Feb 11 '10 at 2:57
Sweeeeeeeet. ;) – techie007 Feb 11 '10 at 3:07
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up vote 2 down vote

For anyone that is looking for the key in Windows 7 it is in one of the folders in:

HKLM\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Configuration\

Look for Position.cx and Position.cy in each of the subfolders; you have to edit the hex string.

Binary / decimal / hexadecimal converter:

http://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html

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up vote 1 down vote

I wish I knew why this worked but I know it does:

To get the monitor to go UP (because negatives aren't allowed by the registry), you have to use values for attach.relativeY like this: 4294967040

Thanks to this forum for helping figure out that part - http://www.ureader.com/msg/164488.aspx

If you change the last 4 digits of that number down, the monitor goes down and vice-versa. This will also work for attach.relativeX. A little tweaking and my setup was back to normal.

Who needs functional drivers pshh

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and thanks to techie007 for getting me on the right path – dfree Feb 10 '10 at 7:07
Sweet, do I get the 'correct answer' mark for pointing out the key? :) – techie007 Feb 10 '10 at 16:35
Can you do half a correct answer? lol – dfree Feb 11 '10 at 2:54
Only if I can give you half a point for your open ended question. :) To me it seems you asked for "any ideas" on how you could fix it by using "a registry key or driver file somewhere" - I pointed out a registry key that you then used to set it. What more do you want? Blood? :) I guess I'll have to include negating 32-bit word hexadecimal number lessons in my next answer. ;) – techie007 Feb 11 '10 at 3:07
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