I want a three monitor setup. Two monitors on a fast powerful card and one monitor on a slower card. They are not linked together, no sli and all that. Can I run a game on all three monitors or will it only run on one card? Will the more powerful card help the slower card? What are my display options. Can I extend the desktop on all three or will the cards have to mirror each other, how does this work?
My experience has been that the graphics cards will not properly show 3D graphics or overlays that extend to more than one screen on the separate card.
In other words, if you show a video (usually done in an overlay) in a window on a single monitor, then move the window to show across two monitors, it will only work when both monitors are either
Similar things happen with 3D graphics, and in many cases you simply can't extend the window beyond the two screens on the better card, or the one screen on the lessor card.
In order to have the best chance at getting this to work seamlessly, use cards from the same manufacturer that use the same graphics driver - which usually means using cards within the same family.
However, if you really need to use three or more displays with advanced 3D rendering across all three, you should look at video cards that explicitly support this feature. Both ATI and nVidia have cards that will support this usage.
I would suggest trying it. I'm not sure, but I guess that it will either:
a. Not work on more than one monitor - This depends on the game.
b. Work at the speed of the slower card - Like RAM, I'm guessing that it's likely for this to result. (When RAM is mismatched, the slowest speed prevails on all sticks.)
c. Work at the speed of each of the cards, depending on the monitor - Each card may try it's hardest, but your results will vary depending on how slow that weaker card is. You may be just fine in this case.
d. Work on only one of the graphics cards at once. - This may be enforced by your OS or drivers, to prevent strange things from happening.
e. Strange things may happen.
Assuming that the game dosen't support multiple screens (the only one i can think of is the supreme commander series), you're best off using a single video card with something like eyefinity, that supports, and renders everything as a single screen as far as the game is concerned.
Alternately, If you're all PCI-E, you might be able to use one good card, and a few cheap ones along with SoftTH to software render the game into running multi screen.
It depends on the video cards, the OS, and the driver settings.
Most video cards (eg ATI, NVidia) with more than one output allow you to use “clone mode” where each output, ie monitor, displays the same thing (this is usually most useful for presentation/kiosk type things).
Some (read few) games support multiple monitors, similar to the Nintendo DS. (I recall that Serious Sam allowed you to play multi-player using separate monitors.)
You can extend the desktop across the monitors, but when you do so, games (or other fullscreen programs) that do not specifically support multiple monitors will simply use the primary display and the other(s) will continue to show the desktop. If the game does not properly capture the mouse, then moving the cursor towards another screen could cause the game to lose mouse focus (and thus cut your in-game control), and if you happen to click while the cursor is on another screen, the game will pause and/or switch out to the desktop (on the primary display) and/or continue on its own without your having any control. Fortunately, most games (especially these days) do properly capture the mouse.
What you can then do in a setup like this is to have a some kind of information or something on the other screen(s) like email, eBay, game walkthrough, etc.