How to connect more than 2 monitors to one pc?

Hello Experts,

I have a new custom built computer which has onboard dvi and vga ports and I also have 2 ATI Radeon HD6450 video cards in it.  I have 2 monitors set up running an extended display, but I would really like to be able to use 3 or 4 monitors in extended display setup.  When I plug the 3rd monitor in, nothing is displayed on that screen and it just says "no input detected".  My first two monitors are VGA and the third one is also vga.  I've tried using a dvi -> vga adapter into one of the video cards and I've also tried directly connecting the vga of the third monitor into the onboard vga port and nothing works.  When I try to go into the graphics control panel it only identifies the 2 working monitors.  Does anyone know how I can get the third monitor to work with my setup?  Thanks.
Brent JohnsonAsked:
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CallandorConnect With a Mentor Commented:
If Catalyst did not install correctly, multiple monitors will probably not work properly.  Try removing the driver first using Control Panel, then make sure your .NET Framework is updated, then install the correct driver for your cards and OS:
Reece DoddsCommented:
so you have an integrated mainboard but are using two HD6450 graphics cards (in PCIe slots)?
If this is the case, you cannot use the onboard graphics, but each HD6450 should be able to output two monitors.
Reece DoddsCommented:
your monitors and the variant of the HD6450 may be your limitations though...  you will probably need displayport capable monitors or at least DVI monitors with an activedisplayport-to-dvi adapter
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Brent JohnsonAuthor Commented:
The video cards that I have do not have display ports.  They have 1x dvi, 1x vga, and 1x hdmi ports.
Standard convention is that most motherboards will disable the onboard video if a discrete video card is detected.  There are exceptions, but for the most part, this is true.  You should be able to get four monitors using the two HD6450 cards and DVI-to-VGA adapters.  Make sure the monitors are on before turning on the pc; some cards turn the port off if they don't detect anything connected to them.  You can only use two of the ports on each of the HD6450 cards at a time.
Rob KnightConsultantCommented:

HD 5000 and 6000 series cards support up to 3 simultaneous displays but only if they are DisplayPort variants.

Your setup should support up to 4 monitors - makes sure that CrossFire has not been enabled by default - this will only output to 2 monitors but use both GPUs (i.e. both cards).


Brent JohnsonAuthor Commented:
Update-  So I've tried using vga > dvi cables as well as vga > dvi adapters and I still cannot get my third monitor to function.  I wonder if this has something to do with it, though... The catalyst control panel software is not functioning right.  I've tried uninstalling it and reinstalling it and whenever I click on the software to open it, it will give me the hour glass for a few seconds, then nothing.  It won't open.  Also when I reinstall the software, it will just sit on the "loading" screen and not go any further.  Any ideas?
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