[quote='RobeK',index.php?page=Thread&postID=137782# post137782]I also had this problem. After installing another card in my machine the fps actually went down. After a good night sleep I finally came to the conclusion why. ALL WOW INSTANCES RENDERS ON THE PRIMARY DISPLAY. Oh yes, you are only using ONE card.
By forcing windows to shuffle the rendered screendata over to the other card to be placed on screen number two actually lowers the bandwidth. Yea sad but true.

SO NOW WHAT?

I asked in the technical forum how you can force WOW to open on a particullar display device but as you all know... Blizz support is what it is => no reply.

I read up on how DirectX functions. Default is that all 3D accelerated windows opens up on the primary screen if the callee doesn't request a specific one. That fact gave me an idea and I finally I got it to work by switching the primary display around.

This is how to do it:

Switch primary to second monitor. Start instances you want to render there. Switch primary back to main monitor (and hope the game doesn't crash. On my system it is a 20% chance of that). Then start the main instance of wow.
You now have WOW rendering on different cards and much better FPS.

To simplify the process I use UltraMon (You should use it just for the taskbar on both monitors anyway). I create two display profiles that only differ in what monitor that is the primary display. I then bind a hotkey to each profile.
Now is switching primary display a breeze.

Happy boxing.[/quote]
Welcome to the club!

[url='http://www.dual-boxing.com/forums/index.php?page=Thread&postID=34403#post34403']Horizontal Span vs Dual View on nvidia[/url]

btw this works with pretty much most of the games.
right now im using 9600gt for my 3 wows and 8800gts for my main wow, only thing holding me back now is my cpu .