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Dustin, Computer Support Specialist
Category: Computer
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Experience:  I speak PC fluently, so you dont have to! Worked in The US Army as A Network Switching Systems Operator/Controller
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I am trying to connect a third monitor to my PC using a USB

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I am trying to connect a third monitor to my PC using a USB display adaptor. The PC is a DELL 530s desktop. I am connecting the monitor, a DELL 1907FP, using a VGA cable to the VGA port on the display adaptor, but when I do so no picture appears on the monitor and I simply get the "colour test" sign on the screen.
Welcome to

My name isXXXXX am one of the experts who will assist you today!

Have you tried to extend the desktop to the third monitor yet? If not.

  1. Right click on your desktop and select properties. Choose the settings tab.
    • Two square boxes representing your monitors are shown.
    • Your primary monitor is labeled 1 and the Secondary or external monitor is 2. Monitor One is highlighted by default. Since your talking about three monitors, you should see three boxes on this page..
  2. 3 Extended view Check Box Extended view Check Box Click on the external monitor 3 to highlight it, then check the box beside “Extend my windows desktop onto this monitor" and click OK.
  3. 4 Desktop View 1 Note that everything has worked properly. Your primary monitor should still be the same and your external monitor should just have your desktop without icons.
You should be good to go at this point, if you dont see the screens im refferring to, let me know.

Please click accept to show I have assisted you.

If you still need assistance, You can reply to this message at any time.

Customer: replied 6 years ago.

Thank you for your answer. Since this is a complex problem I will give you a bonus if you can help me to sort it out.


Your suggestion unfortunately didn't work. When I attach the third monitor the PC shifts my two previous screens to the left, so what was the central screen becomes the left-hand screen (i.e. the new third monitor attached by USB adaptor) and what was the right-hand screen becomes the central one. Meanwhile the left (third) monitor resolutely remains dark. This means I can't adjust any of the settings, because everything disappears into the dark 3rd monitor, which the PC believes is my main monitor. In other words, if you open the display properties box it opens in the dark 3rd monitor. I have tried moving around the monitor icons in the display properties box, but nothing works.


Any ideas?

Ok. yes, i do have some ideas..

This is all going to be on which monitor your set as default..

and those keys to unlocking the issue are going to be in those boxes. 1 , 2 , 3

instead of moving the icons around.

You will need to click on the icons, and then click set as default..


And I should have asked before.. Have you installed your own graphics cards, to allow three monitors?

if not, you will need a card like this, that supports up to three displays..

There are many cards out there, so depending on the connector types of your monitors, you may or may not need a different card..

Let me know what you have, and if you have a card made for three displays, or if you have a dual card situation..
Customer: replied 6 years ago.


Thanks, XXXXX XXXXX do I find "set as default"?


Also, as I said in my first post I'm trying to connect using a USB display adaptor. My graphics card is a dual card.

That is the issue then.

Im sure thegraphics card works great with two monitors.. as that is what it is made to support

However .. to use three.

There must be something that is controlling all three, telling each one what position it should occupy.

Sometimes windows can do this..

So far though.. if you have all three monitors, and its not working.
We can keep tinkering with settings, but it is highly probably that you need either two dual cards that can interface.,. or one triple card..


  1. Click Start, and then click Control Panel.
  2. Click Appearance and Themes, and then click Display.
  3. On the Settings tab, click Identify to display a large number on each of your monitors. This shows which monitor corresponds with each icon.
  4. Click the monitor icons and drag them to positions that represent how you want to move items from one monitor to another, and then click OK or Apply to view changes.

  1. On the Settings tab of the Display Properties dialog box, click the monitor icon that represents the monitor you want to designate as the primary monitor.
  2. Click to select the Use this device as the primary monitor check box. Note that this check box is unavailable when you select the monitor icon that is currently set as your primary monitor.
now you have set your primary monitor.. Which you probably should make the center monitor.. But it also usuall needs to be the monitor connected to your main Vga out port..

Customer: replied 6 years ago.


I've tried all of this but it doesn't work. As soon as I connect the 3rd monitor the computer thinks it's monitor 1, no matter what I have done with the icons before. Of course, if the Dell monitor would wake up it would't matter as I could manipulate the display properties box on the 3rd monitor. But instead it remains stuck in darkness, even though the PC obviously thinks it's working.


Part of the problem is therefore the fact that the Dell monitor will not respond. I have another monitor, an ACER, where it DOES work, but I prefer the Dell because of the image quality.


End of the road?

I believe so..

Question though.. you mentioned the dell does not work, but the acer does..?

What type of connection does the dell have

and what type of connection does the acer have?
Customer: replied 6 years ago.
They are both connected via VGA to the USB display adaptor

If the acer and the dell are both connected the same way.. and one works, and the other doesnt..

Then that seems to be that its not so much an issue with the settings, it seems like just the monitor..

what happens if you take the dell..

and connect only it, and then disconnect the others, and then restart the computer.

Will they dell work in standalone fashion?

will it work with just dual monitors?

Is it only when you add the third that the dell quits?
Dustin and 6 other Computer Specialists are ready to help you
Customer: replied 6 years ago.
I gotta go now but will respond in next few days, thanks for your help so far.
No problem..

Wish i was there in person, Im pretty sure this is a settings issue.. and a matter of connecting the correct monitor , and then connecting the next monitor.. Of course, the triple view graphics card would be nice.. But we may be able to work around that.

Look forward to your replies in the next few days..
Customer: replied 6 years ago.
Sorry for the delay, I will get back to you on this, I have just been busy
I understand completely. Take your time, get back to me when you can..

Happy Thanksgiving!

Customer: replied 6 years ago.

Hello again

I have found a workaround for the problem as follows:


1. Turn on PC

2. Take out VGA cable of 2nd monitor from dual graphics card and plug in 3rd monitor instead. After a few seconds, swap back and plug the 3rd monitor into the USB monitor adaptor

3. The 3rd monitor has now been "woken up" and remains alive after being plugged into the adaptor. The position, resolution etc. can then be controlled using the normal control panel options in XP.


Having done this a few times the 3rd monitor now seems to realize it's supposed to be awake and comes on even when plugged into the adaptor at start-up, in other words I no longer have to switch the plugs around.


So the problem comes down to getting the DELL monitor to get out of sleep mode and/or getting the PC to expect that a third monitor is attached.


I think this is the problem solved now. Do you have anything you want to add?