I guess you realize that with these lower-end cards you'll really have to drop the visual quality to game on multiple screens.
Personally, I'd far rather game on a single monitor with much better graphics quality.
Crossfire/SLI:
1) Both introduce micro-stutter which is NOT insignificant. Can provide latest links.
2) SLI is superior to Crossfire in performance and number of profiles.
*My advice:
Take the money for those extra two monitors and put it towards a better graphics card and play on a single screen.
Graphics Card:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202026
Why?
- two free games (digital download) of CRYSIS 3, and Bioshock Infinite
- quiet, good cooling
- great reviews
Monitor:
Just FYI, but I looked into a 3x setup but there were too many issues. I ended up buying a 27", 2560x1440 from Dell (they have a great one for $700). I often game at 1920x1080 even with a GTX680 as there's little visual benefit to 2560x1440 but a 30% performance hit. I game at 2560x1440 for Diablo 3, Starcraft 2, Torchwood etc (basically games that benefit due to smaller text that can still run at 60FPS).
PROS and CONS:
There's no "perfect" gaming setup but in general the best solution is:
- 60FPS VSYNC'd (ignoring 120Hz screens)
- best quality settings game offers
- no stuttering
Gaming with three monitors is fine if you have the hardware to achieve the above but you don't. Therefore sacrifices have to be made. Lower frame rates. Lower quality visuals. That's a big sacrifice just to get three screens.
SUMMARY:
For $300 you can get an HD7950 that comes with two great games as well (so the card costs under $200). You can SELL your GTX460 as well for a little money.
My advice again, is get this card and game on a single monitor.