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I have total 3 monitors.

I have ATI Graphics card with 3 ports.
2 HDMI and 1 DVI (looks like).

                       (Video card port    -->  Monitor port)
 1)   HP L0245W          (connected DVI      to   VGA         )(working)
 2)   HP L2045W          (connected HDMI     to   DVI         )(working)
 3)   HP Compaq LA2205wg (connected HDMI     to   HDMI        )(not working)

if I unplug cable 1 from video card then monitor 3 works,
if I unplug cable 2 and plug 1 back in then 3 works.

How can I get all 3 working ?

This is video card I have ATI HD4600
Photo of Video Card

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Your video card does not support hooking up three monitors at once. – Ramhound Jan 28 '13 at 17:28
up vote 5 down vote accepted

Sorry, that graphics card only supports 2 simultaneous monitors.

Edit: If you're willing to spend some money, you could go for something like a Matrox display splitter (, but for that price you may as well just buy a new graphics card that supports triple monitors. (random example) There doesn't seem to be a software fix to this problem, it's just a limitation of the availible hardware.

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that is so messed up, why do they even put 3 ports on it. thanks for info.. how can I get 3rd monitor to work? I also have a built in VGA port on motherboard can I use that? – user635600 Jan 28 '13 at 15:17
Hmm, what are the specs of your computer (specifically CPU and motherboard, that might enable graphics on it?) – Marcus Chan Jan 28 '13 at 15:21
4 GB Ram, 3.16Ghz, what info do you need? – user635600 Jan 28 '13 at 15:24
Well, for your motherboard to have graphics output capability, to my knowledge, it would need either an Intel Core i3/i5/i7 CPU, an onboard integrated graphics card, or an AMD A-series APU. Does your VGA port work by itself? – Marcus Chan Jan 28 '13 at 15:26
@Offler See MarcusJ's comment on the other answer (no relation :P); cards with Eyefinity support will run 3 monitors simultaneously, and that's most of the current generation. – Marcus Chan Jan 28 '13 at 16:08

Well, firstly have you verified that all three monitors work on their own? Also make sure that your video card supports driving three monitors at once.

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Yes, they do, I use to use 3rd, monitor with laptop via HDMI and on my desktop if I unplug first monitor 3rd and 2nd monitor works, how do I know my video card supports 3 monitor at once? my video card has 3 ports. – user635600 Jan 28 '13 at 15:14
You have a few options, if you're not going to be gaming you can use the integrated GPU (assuming your processor has one, and your motherboard has an available output) you can also buy a newer GPU (make SURE it supports driving 3 monitors, Eyefinity is the marketing name from ATI associated with driving 3+ monitors). – MarcusJ Jan 28 '13 at 15:21
I use it for work :), I do not want to spend my own money on works computer, there is a built in VGA on my mother board. – user635600 Jan 28 '13 at 15:24
Then you should be able to plug in your third monitor on the VGA port Protip: plug in the lowest res monitor into the VGA port. – MarcusJ Jan 28 '13 at 15:27
Gooling for the manual yields this page:… then in the specs part of the page: two independent display controllers Drive two displays simultaneously with independent resolutions, refresh rates, color controls and video overlays for each display --- So this ATI card can only run two of them. For more you either need an extra GPU (and drivers and OS support), or a card which supports more simultaneous outputs). – Hennes Jan 28 '13 at 15:31

This is because the DVI and the HDMI output are the same with change at the connector end. In order for DVI to work, the circuit is directed there cutting off the HDMI output and vice versa. All you need is a second graphics card (if you have another PCI-E 16x slot) to have more outputs. As a last resort, you can use a legacy PCI graphics card (you are not limited to very old cards, I have found a Zotac Geforce 610 PCI card, others may exist as well!) but performance will suffer because legacy PCI slots are too slow by PCI-E standards (16 times slower or more!)

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