How To Dual Monitor Eyefinity with Center Offset

[TheAcorn]

I ran across an old post concerning running a dual-monitor setup with a center-offset, as to not block the center of vision with bezels. I recently found a really weird but working solution for this problem for AMD users, and USAFRet suggested I make a new thread for this solution, instead of necro-ing, so I suppose I'll post it here instead.

AMD GPU users can use Eyefinity Pro + 2 displays + a dummy display (HDMI dummy dongles can be had for ~$5). Ideally, the two real monitors have an indentical ppi (pixels per inch). The setup in Eyefinity Pro involves using the dummy display as a third monitor on the side in which you want the center offset to. For explanation purposes, I will use LMonitor (left monitor), RMon (right monitor), and DMon (dummy monitor) to describe the layout.

Say I want to use two screens to play a game with the center of the screen offset to RMonitor:

1. Calculate the pixel position of your desired center-screen. If LMon and RMon are 1920x1080p, the default center-screen position across the two-monitor 3840x1080p space is at pixel [x = 1920, y = 540]. If I want the new center-screen position to be offset by 1/3 of the horizontal space of RMon, then I must add 1/3 of that monitor's horizontal resolution to my desired center-screen, i.e. 1920 + (1920/3) = 2560 such that the desired center-screen position is now at [x = 2560, y = 540].
2. Now that you know your desired center-screen position, double the horizontal component of said position. In my example, this would give us 5120, which is our desired horizontal render resolution (since the halfway point of this width is 2560). Subtract the sum of horizontal REAL monitor resolution from this number. For example, 5120 - (1920*2) = 1280.
3. The new number (i.e. 1280) is the horizontal resolution that you must target with DMon. There are two ways to achieve this:
   • Firstly, in my example you can use a dummy monitor resolution of 1280x1080p (if possible), and set DMon to the right side of RMon (since I want to offset to the right) in Eyefinity Pro.
   • Alternatively, if you cannot set the resolution, you can set DMon to overlap with RMon in Eyefinity such that the difference in horizontal DMon resolution and the overlap amount is equivalent to the target horizontal length. In my example, if Dmonitor is 1920x1080p, 1920 - overlap = 1280, so overlap = 640. Apply this overlap in the negative x-direction (-640) on DMon to have DMon overlap to the left.
4. Click Apply and you should end up with a single virtual monitor that spans across two real screens and extends into an invisible third screen (DMon). The resulting display should resemble the image attached below.

Disclaimers and Notes:

• I don't know why, but the Eyefinity Pro overlap is finnicky and sometimes the overlap is not true to the user inputted overlap. It may take some trial and error to find the right amount of overlap to get the right center-screen position. Make an image in mspaint of, in my example, 5120x1080p and draw a marker in the center [x=2560,y=540]. Use this as your desktop wallpaper for center alignment testing.
• HUD elements may extend into the dummy monitor space, so this method only really works with games that allow you to limit HUD screen space or customize HUD position (with mods or vanilla).
• There are added performance costs to this method. You will not be able to see what is displaying on the dummy monitor, but the internal render resolution still includes this space, so there is added rendering cost.
• Some games do not play well with Eyefinity Pro, and may crash on alt-tab or resolution/aspect-ratio changes. May also crash display drivers.
• You can potentially connect your GPU video output to a capture card input, effectively using the capture card as a dummy monitor.
• In Windows and most Linux distros, Win/Super + Shift + Arrowkey can manipulate the position of a window. If a window escapes to the dummy monitor and you cannot see it, try alt-tabbing into the window and using this shortcut to move it to a real monitor.
• If your Windows gets stuck in Eyefinity mode, open Adrenalin: Settings>Display>Scroll down and click "Discard Eyefinity Setup"
• I am not responsible for any damages to your computer and peripherals, try at your own risk. I don't imagine it would brick your GPU or monitor, but there's always a miniscule chance for something to go haywire.

I like to use this setup with my two 2560x1440p monitors and my capture card (stuck at 4k when using Eyefinity) to offset the center of my screen in racing games. I align the bezels with the left-side A-pillar of the car (in cockpit(?) view) to minimize the loss of useful information while retaining left-side peripheral vision and left mirror vision for added immersion.

Props to USAFRet for pointing me in the right direction instead of just deleting my comment!