I'm now running a 3-screen setup on my stock 700-plus series Dell, running two GeForce 7900 GTX cards (dual heads each, 512 mb each) and 4 ghz of RAM, and one 24-inch Dell widescreen digital monitor. I was running these in SLI mode until I hooked up my additional screens. Btw, my 3-screen setup may be one of the odder types out there:
For Christmas, my oldest son gifted me a used Wacom Cintiq 21-inch flat panel/screen tablet. My wife, having heard my oohs and aaahs over other people's 3-screen setups, gifted me with a Dell 2208 22-inch digital widescreen flat panel monitor. However, the Cintiq is a digital graphics art tablet which doubles as a monitor. At first I wasn't even sure I could make these differing units work on my then-current setup so that I could play Aces High.
Having tapped out whatever budget and wifely goodwill I had in reserve for this, I downloaded SoftTH (free utility), because the TH2Go was out of the question, budget-wise. However, for SoftTH to work, you can not run dual cards in SLI mode, so that meant a single 7900 GTX would have to carry the processing workload while the second card acted as a simple connection passthrough for the third monitor. In this setup, they can't be SLI'd.
Happily, with just a bit more fiddling than I would usually do for any new gizmo on my machine, I made this all work. The Cintiq is 21 inches and 4:3 aspect, and is on my left (for ease of use as a tablet), while my center monitor is 24 inches, 16:10 and the right side side panel is the 21 inch LCD, also 16:10 capable. All of them run at 60hz. Again, I can't run these in SLI with SoftTH, but even with the one 7900 GTX card doing the processing, I get near 60 FPS in regular play, without any changes to the in-game settings I had in place before adding the other monitors other than setting a wider resolution and FOV. I do recommend updating Nvidia drivers however, to make sure you have the latest that support multiple screen setups.
SoftTH's settings took a bit of tweaking, but not as much as I expected. I don't think I have the best possible settings figured out for resolution, aspect, and FOV, but I'm almost there, and the current settings are pretty good, and extremely immersive. I called my set up odd because most Cintiq owners probably don't use theirs for gaming in 3-screen setups. The differing aspect ratios and max native resolutions is a bit tricky to synchronize, and the Cintiq's wide bevel and lack of full 90 degree range of tilt capability makes getting the setup to feel right kind of difficult. However, I was pleasantly surprised that the 7900 cards are working out just fine with AH. This might not be the case with say, COD4 or COD5, because their graphics demands are much higher, but since I usually only play those in multiplayer mode, I can't run SoftTH with them anyway (Punkbuster kicks you when you try it). For those games, I simply run them on a single screen. I still can't take full advantage of having both cards SLI'd for those games, but I don't play them as often as AH either.
So, to sum up, if using SoftTH, two dual-head 512 mb 7900 GTXs with updated drivers SHOULD work, non-SLI'd, with varying qualities of framerates depending on the game. Aces High II runs fine with my setup. (Caveat: I run a bit extra system RAM, at 4 ghz.). Hope that helps.
