Current State of SLI Support is broken across all Linux Distro's

Graphics / Linux Linux
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Hello everyone, I will do my best to be brief regarding my current observation(rant warning) of SLI support across multiple Linux Distro’s So far I have tested several popular distributions with the following configuration:
CPU: Core i7 4790k@4.0GHZ(Stock)
Memory: 24GB PC3 1333MHZ DDR3(ADATA, and PNY)
Storage: 1 Intel 520 160 GB SSD(Primary OS/Boot drive)(EXT4)
1 Samsung 840 Pro 250 GB SSD(EXT4)
2x 1TB Western Digital Black(EXT4)
Motherboard: MSI Z97 Gaming 5
Video Cards: 2x EVGA GTX 970’s(SLI)
2x PNY GTX 670’s(SLI)-

For Testing/Comparison purposes, all cards where tested using Windows 8.1, and Windows 10 in the past without any graphical glitches/artifacts/defects/bugs using the most recent drivers as the above hardware configuration.

Let’s get down to the Distro’s Tested:
Linux Mint 17.1(Cinnamon Desktop Environment)
Ubuntu/Lubuntu/Kubuntu/Xubuntu 15.04(Various Desktop Environments Tested)
Fedora 21(Gnome Desktop Environment)(Using Kernel 4.0.X+)
Debian 8.1.0(Various XFCE, GNOME, and KDE)
OpenSuse 13.2(KDE)
Arch Linux (Using Kernel 4.0.X+)
SteamOS

SLI Rendering Method’s Used(based on nvidia-xconfig): AUTO, SLI=ON(same as auto) AFR, and SFR.
Note: MultiGPU was set to OFF. While enabling SLI is supported, the observed pattern represents, graphics bugs, glitches, ghosting/trailing, crashing/failing of X-server, and up to a -50 percent performance spec when compared to a single card configuration.

After testing against the listed OS’s above and no matter the system configuration, or even driver installed(testing was also conducted using 2 previous driver versions) SLI is severely broken or incomplete. Either the UI would fail to properly render graphic assets(trailing/ghosting/etc), or performance was degraded to the point of simply having to disable SLI all together(always resulted in fixing the problem). The testing was done on both my 970’s, and 670’s, and all drivers purged prior to the installation of new hardware. One of the main reasons/considerations of switching to Linux was speed, security, flexibility, and reliability, unfortunately at the sacrifice of performance regarding graphics acceleration. Has anyone else been able to successfully use SLI(does not matter the video card) against any distro without experiencing artifacts, drawing, utilization or performance issues? Given the amount of time that has past(sli has been around since 2008), and my past experience with SLI problems in Linux I figured these issues would have been resolved by now(apparently not even by a long shot). Finally, the most alarming part about this issue is the fact steam machines with SLI configuration’s are on the future lineup for consumers to purchase … Given the lack of functional SLI support, people are going to be in for a world of hurt, when there Steam Machines provide far below the expected level of performance when running SteamOS(Ubuntu/Debian derivative). I contend this to be unacceptable, and absolutely terrible given the implementation of SLI started of 7 years ago, yet nothing has been done to fix the well documented issue’s with multi gpu systems running in an SLI configuration.

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Intentionally populated for future use…

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Future Use.

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So far from what I’ve been told already here in this forum the only way for SLI to work on linux is to have several monitors and SLI enabled in mosaic mode, so that each gpu renders its own x-screen.

For my case(single monitor use), enabling SLI on AFR or SFR will either make the windows flash all the time or cause tearing, it’s so bad, it gets to the point where I open up a new window and have a stain on it that is a bit of the old window, anyway enabling SLI on either of these modes will make the desktop unusable for my setup (2*GTX760), so I just enable it on AA mode to pretend that the second card I’ve bought actually makes something, however it has the inconvenience of dropping frame rate on csgo by about 20-30fps and making resuming from suspend not working(at least on fedora).

The alternative is to leave SLI Off and use the second gpu for a KVM VGA-Passthrough to play games on a windows VM :P
https://bbs.archlinux.org/viewtopic.php?id=162768

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My understanding is that the Steam Machines with SLI cards will have Windows installed.

Currently SteamOS doesn’t even support SLI: nVidia SLI for Linux not working in SteamOS · Issue #224 · ValveSoftware/SteamOS · GitHub

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anyword about the nvidia sli state in linux?

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Main problem with SLI afaik is that you don’t get the speed ups for free with the driver. You need SLI profiles for the games you are playing and there simply aren’t that much for Linux (I only know of SLI profiles for Doom3 and Serious Sam 3). Similarly while there are per game driver level optimizations for DirectX games on Windows with the GameReady driver, there aren’t any (or only very few) game profiles for OpenGL games on Linux.

Hopefully this will change with Vulkan, where much of the driver complexity is pushed to the application so the game developers have to make sure that their renderer can use multiple GPUs and then it should “just work”.

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Dear NVIDIA!

Please tell me us what is the current state now.

Best regards!