It doesn't matter if you're using the full resolution of your monitor or not. In my Multiboxing with MiRai videos I use a 1920x720 resolution and all that matters is that the game clients are the same resolution -- Which normally means they'll have to be stacked. It's just usually referred to as "fullscreen stacked" because the preset in the ISBoxer Window Layout Wizard defaults to stacking all of the clients at the full resolution of the user's monitor.

Quote Originally Posted by rfarris View Post
I'm curious about which one puts a heavier load on your graphics system -- one monitor running 2560x1600 with 1920x1200 char windows stacked and videoFX windows around the edges, or having two monitors running at 1920x1200 with the main monitor running full screen stacked and the videoFX windows on the other monitor. I suspect that the two monitor scheme would look like a 3840x1200 display (total of 4.608M pixels) as opposed to the 2560x1600 display (4.096M pixels). I don't know if that's the only consideration, though. For instance, on the second monitor I only used a 600x1200 videoFX window. Does that matter, or is it the total available image size that matters?
I can't imagine that the total size of the desktop has much bearing on whether or not there will be extra load put on the GPU. Load is determined by the amount of pixels you're using in each client's resolution, and if all clients are using 1900x1200, then they're going to put the same load on the GPU (+/- 10%) regardless of monitor size. The only time this most likely won't hold true is if your desktop is using nVidia Surround (I've no idea about Eyefinity) because for some reason, Surround seems to put more load on game clients for no reason at all.