Multi-Display Rendering on 8 screens is laggy

Hi all,

I'm having issues with my project which has 8 display outputs. I'm using the MultiDisplay rendering outlined here:
http://docs.unity3d.com/Manual/MultiDisplay.html

I've followed the instructions and it looks like it would be perfect for my setup, but the outputs get significantly more slower with every screen I add. With 2 screens there's no problem, but up to 4 screens and I can see a sync'ing issue where the game hiccups periodically for very short amounts of time. With 8 screens it becomes definitely noticeable that the game is lagging with severe hiccups, but putting in an FPS counter, Unity doesn't report it ever dropping below 60 FPS.

Can anyone give any advice on this problem? I can post more about the issue, too, if that will help.

 

FYI. If you are doing this with USB -> DisplayPort / DVI / HDMI there is no real solution. USB (even 3.0) is not designed to handle isochronous streams very well. It is interrupt driven and takes linear time to render your screens (it just the CPU rendering them all).

I did a kiosk which had multiple screens (6) and we ended up using some of the multi port NVidia cards for signage and financials (4 ports/card) in addition to the main video card (2 ports - DP and HDMI)

 

Thanks for the reply. The computer is using two graphics cards with 4 outputs each that are powering the 8 displays, no USB adapters involved. It is using two Quadro M5000s and a Quadro sync card, so I suspect that they should be more than enough to handle the 8 outputs, especially since the game starts to lag on even 4 outputs. I'm just not sure whether it's a Unity issue, or if it might be the fact that this is in Beta, or if it's a graphics card issue.