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I am looking to buy a new video card to power two identical monitors. The monitors came with both DVI and VGA cables, so I am able to use either.

My current video card has two DVI ports on the back, so I have both monitors connected via DVI at present. I have noticed that many modern video cards have a DVI/VGA/HDMI port trio and that cards with two DVI ports seem somewhat more scarce. Essentially, I have more options available to me for purchasing cards with a DVI/VGA/HDMI trio than with a DVI/DVI duo.

My question is, are there any sound reasons to go to the extra effort of finding a card with two DVI ports versus simply running one of my monitors through a DVI and one through a VGA on a DVI/VGA/HDMI card? Quality differences? Any variety of image asymmetry? Configuration difficulties (I dual boot Windows and Ubuntu)? Anything else?

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DVI and HDMI are digital output, VGA is analog. Digital output will be superior to analog for clarity and color matching.

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I'd add that in nearly all dual dvi ported cards, one is a DVI-I - which does VGA as well with a passive adaptor. A lot of high end cards also have DP, which is roughly analogous to HDMI, and have multiples of those. – Journeyman Geek Sep 2 '12 at 4:04
    
display port is a bit of a pain due to needing adapters to get to most devices. dell switched from dp to hdmi on their latest releases due to so many tv's etc having a hdmi port but no dp. – Kendrick Sep 2 '12 at 4:18
    
@Keltari related question - what if I were to use a HDMI-to-DVI adapter on the HDMI port of a DVI/VGA/HDMI trio card? Would this give me comparable quality on both screens, or would the HDMI-adapted monitor now have different characteristics (for better or worse) than the pure DVI monitor? – Bryce Thomas Sep 2 '12 at 4:21
    
Thats the beauty of digital signals, converting them will cause no loss of quality – Keltari Sep 2 '12 at 4:39

It comes down to what displays you have and or plan to use. if you have a very nice crt that does high refresh rates well for gaming you would want to keep the vga port so that you could use it.

If you have dual/tripple input lcd screens you would want to go with digital due to picture quality. If I put the display tuning wizard on both screens when it goes to the color test partern you can very visibally see about 10 vertical "lines" about 1/2" wide on the analog lcd due to noise being picked up on the wires. the cable is 5' or less to my case.

Once I rack this system I plan to put them both on dvi due to 15' cables being needed.

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You can buy a cheap (for maybe about $5) female HDMI to male DVI adapter or male HDMI to male DVI cable, so you'd not need to use analog VGA with DVI/HDMI/VGA card. HDMI can also output sound, which can be useful sometimes (for example to connect PC to big TV, or to a monitor with speakers).

So DVI/VGA/HDMI is better for you.

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Yes, go for 2x DVI-I ports and you can use them both with a VGA adapter, giving you all freedom. – DanMan Sep 2 '12 at 10:30

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