After plugging in my second HIS Radeon HD7850, I seem to have the weirdest issue.. a ghost area of screen-space.. take a look at this screenshot: https://dl.dropboxusercontent.com/u/...-WindowGap.JPG
Annoyingly, most tertiary interfaces in any design software I use, seem to get stuck on it, often including ones Win+Directions or the Alt+Space trick don't work on, so now I'm having to resort to taking screenshots and trying to blindly click+drag them out of the void.
In the Screen Resolution controls, the gap is not there after I drag a window; it snaps into place, but as soon as I click apply, having moved a window, just changed the Main Screen, or both, the gap appears, always to the left of whichever is the Main Screen.
I've measured it with the Snip tool, it's 762x1022 regardless of the alignment of the monitors, and has my desktop background centred as though it was a monitor.
The resolution of most of my screens is 1920x1080, though I have a TV connected at 1280x960.
I used all of these screens in any combination prior to installing the second GPU without any such issues.
When the furthermost left screen is the Main Display, the gap is of-course to the left off-screen, not obstructing my mouse movements, but interfaces still get stuck there, and I don't want to have to keep that screen on all the time either.
If I disconnect a screen and go back to just 3, the problem persists..
I've got a 2560x1440 on the way & and a longer cable to reach my last screen, 1280x1024, so in a few days we'll see how it reacts with 6 screens, but for now I can't really test any more.. if it's really worth trying, I could try a 5th now, but the number of monitors doesn't seem to affect it.