Anyone managed to get Nvidia SLI running at 4k without major issues?

Been trying to get this happening on my dual 980TI rig,
I have a Wasabi Mango 49" 4k screen and a portrait 900p screen to the right side.
I'm using OpenBox on Ubuntu 16.10 with latest drivers (kernel4.8)

Issues I have encountered so far:

-Enabling SLI/MultiGPU in xorg.conf causes second screen to be disabled and the 4k screen to be stuck at 30hz. SLI shows as active in the nvidia-settings control panel.

-Nvidia talks about this MOSAIC SLI option but for me it only has the basic version which is for single card setup, no option shows up for SLI for this mode (as mentioned in their notes, this a premium feature?)

-Sometimes when attempting to enable the second screen I will instead get a extended PAN view on the 30hz 4k screen (because I can't select 60hz as it doesn't exist).

-I have attempted to connect the 2nd monitor to the second GPU but that didn't seem to change anything. The 2nd monitor does show up in non-SLI mode for use just fine.

-I have had some partial success with "Xinerama" but here's the catch, RandR fails and doesn't work, no solution found and its a critical component for allot of apps ;-(

PS. I'm not using TwinView option as I only want my 49" to be used for gaming.

I have heard that sli is not well supported under Linux and I have never tried it my self but I found this article that might help you out.

Thanks but I already read this.

I did get sli working on linux. Granted, I was using older cards - two 660's at the time. But, the way I did it to finally get sli working was install one card and do a fresh install of linux. Shut the pc down install the second card and apt-get update, apt-get upgrade then update the driver then sli should work.