Can't you just install 3 cards that each have dual DVI ports?
I think the only requirement would be having enough slots in the motherboard, but I think having 3 separate PCI-E 16x slots is becoming more common.
NewEgg.com seems to be one of the few sites that allow you to search motherboards by number of PCI-E 16x slots.
UPDATE: Yes, I actually did this recently and it worked great. We wanted to avoid DisplayPorts because they can get so loose and flaky and as soon as one is unplugged, Windows recalibrates the multi-monitor setup and everything goes haywire. With DVI ports they can be screwed in which is so much better.
We looked at getting a Matrox card (or two) with multiple DVI ports but they are quite expensive. Instead we bought 3 dual-DVI video cards (ATI 5770's), a motherboard with 3 x PCI-E slots, a large gaming case (Antec) to support 8 expansion slots (necessary because of the double-slot requirement of the GPUs and the strange layout of the PCI-E slots), and an extra GPU power supply so the graphics cards could have their own dedicated power supply to ensure enough steady power.
(Because of all the extras that were necessary, it probably wasn't much cheaper than buying the Matrox cards, but I suspect full-screen video rendering performance will be better on the ATI's than on Matrox.)
So far it's worked pretty well. Windows 7 detects the six displays pretty easily. I'm not real keen on ATI drivers and software so might avoid them in future (try nVidia perhaps), and have had some crashing problems on our Adobe Air app, but that could be completely unrelated to the hardware or drivers.
Anyway, hope my experience helps somebody else out there.
Simon.
I don't think there are any actual cards with 6 DVI outputs, though. – SLaks – 2010-04-20T14:17:32.503
1But DisplayPort is compatible with DVI; just pick up a few cheap converters. – squircle – 2010-04-20T15:07:19.323
Is there a more affordable solution to this such as a graphics card that has 4 dvi outputs? as i already have one 4650 card and only one more pci-e slot left on the motherboard. – pie154 – 2010-04-21T09:41:39.443
1@pie154 4870 X2 is another option if you can track one down – Shevek – 2010-04-21T10:33:43.533
@pie154, @Shevek: guys, Super User is not The Shopping Channel. listing products that meet a specific technical need is fine, but we aren't here to supply pricing info or where to buy. that's what Google is for. – quack quixote – 2010-04-21T10:52:01.757
@quack quixote: sorry... won't do it again! – Shevek – 2010-04-21T11:01:09.177
@shevek: thanks. i appreciate you wanting to be helpful; keep it up. :) – quack quixote – 2010-04-21T11:09:28.317
3
@thepurplepixel Eyefinity cards have funny rules about DisplayPort connections. You can't just use "cheap" (i.e. passive) adapters. You need to use at least some active (i.e. expensive) adapters. For the 6-port card, it looks like you can use 2 passive, 4 active: http://www.bit-tech.net/hardware/graphics/2010/04/13/ati-radeon-hd-5870-eyefinity-6-review/1
– coneslayer – 2010-04-21T11:23:56.597Yep, coneslayer is right. IMPORTANT NOTE! – Simon East – 2011-04-11T00:32:21.027
Sorry, but how do you get 4 or 6 outputs from the 4850 X2 or 4870 X2? They both seem to be 2-port cards. I think it's only ATI's 5000 series that support 3+ ports simultaneously. – Simon East – 2011-04-11T00:37:04.583
@simon: I mentioned the 4870 X2 as an alternative to the 4850 X2 the OP was looking for, not as a 6 port card. – Shevek – 2011-05-04T11:06:55.143