We are building up a small Digital signage system includes 4 monitors, 1x40", 3x32" Samsung. The content will be played from a single workstation HP or Dell, we need your advise to select the best graphic cards to power up the displays with simultaneous content.
I know that this question has been open forever, but hopefully I can provide further helpful input.
We currently have a system that powers 3 Flat Screens (21" PC monitor, a 46" TV and a 60" TV) from one HP SFF PC for our Council Chambers/Voting system. These use a Matrox graphics card that has one output connector, that splits into 4 VGA signals. I believe it is a member of the M-series, but I can't say off the top of my head.
There's nothing special about 32" or 40" monitors unless you are planning to run fullscreen 3D games on them. I assume this is for regular 2D content? Honestly, any video cards will do ... as almost all video cards have two video outputs (typically DVI) these days, and are plenty powerful enough for 2D at very high resolutions.
But just to be safe make sure the video cards you get have dual DVI outputs:
But, you need to install two video cards to drive 4 displays. (There are some new high end cards from ATI that can drive 3 displays, but they're kind of annoying as one of the outputs is HDMI.)
Thus, the most important advice is to buy a computer with two video card (PCI Express x8 or x16) slots on the motherboard.
I also recommend buying two identical video cards, as mixing and matching video cards can be painful.