SLI with 2X Nvidia Geforce GTX 690 on Ubuntu 20.04 not working...
 

I've just realised that only one of my two Nvidia GEforce GTX 690s is actually working with Linux. The Nvidia xserver app recognises both cards but as far as Ubuntu 20.04 is concerned there is just one card. This possibly accounts for why Skyrim has never run quite so well on Linux as it did on Windows. xconfig is installed but the SLI command is not recognised. I can only set SLI to 'off' and 'mosaic'; not to 'on'. I've tried everything within my very limited powers. Nvidia suggest I have the 'wrong' kernel so maybe that's next on the list. But before I do something drastic regarding Ubuntu (which I like very much), I'd really like some opinions. SLI seems to have a bit of a mixed reputation and some Linux people seem to think it is 'broken' on Linux.If I'm wasting my time trying to get it to work then I'd like to know; and why, if possible. If I should give up and get a new card I'd listen to that too so recommendations as to which (I play Skyrim and take photos and I don't do much else on a computer these days) won't be received with huffiness... Hardware isn't something I know very much about at all (I've replaced graphics cards though) and my Linux knowledge is rudimentary... I don't want a new computer yet as I'm hoping that Bethesda will release TESVI in my lifetime so would rather wait and spec it to fit the game...

Thanks in advance for any help!

I don't know if this will help, but hope is does!

I have my doubts it would.

Tilly, what is the actual problem?

If you are just looking for opinions; then IMHO I wouldn't bother with SLI or AMD's CrossFire since I have zero need to have two or more video cards - one video card is more than enough for me.

TorC - I'll give it a go! Thanks!:)

jsbjsb001 - I guess I want to know if it's possible to get SLI to work on Ubuntu 20.04 . To me it looks as if xconfig doesn't have the command to switch SLI on which is very odd. It simply doesn't recognise it as a valid command although it figures in the instructions to enable SLI. I also wonder if there's something I need to do to get Ubuntu to recognise the second card - or if indeed it can. I think had I understood I'd end up on Linux and where SLI would go (or rather that it seems to have gone nowhere) I'd have had one super duper card too!! I may just have to give this up as a lost cause! Anyway, thanks for replying! :)

From everything I've seen, and this includes playing around with a machine that has two physical GTX 690s and runs QuadSLI in Windows 7, Quadro Plex IV, etc (and can you clarify that: how many ACTUAL CARDS do you have? GTX 690 is 2 GPUs on one card, so when you say 'one of my GTX 690s' do you mean one GPU? I know the nVidia X Server Settings does a bad job of representing this), "SLI in linux" does not really exist. Even if you could get the driver to enable it (which seems to be deprecated - more on this in a bit), it would require application profiles, which only exist(ed?) for a handful of OpenGL games (I believe Doom has one, for example). What the driver *will* offer you is any/all GPUs for CUDA/OpenCL, NVENC, or 'offload' via PRIME (as in, GPU #2 can render while GPU #1 physically outputs to screens), as well as (apparently) Mosaic, which is nVidia's proprietary multi-monitor/GPU thing (I honestly forget exactly what its claimed advantage is over Xinerama/PRIME but it achieves essentially the same goal - multiple GPUs driving multiple monitors, with one GPU doing all the 3D work (assuming you're running 3D) - on Quadro (with 'Quadro Mosaic') the advantage is you can (physically) sync everything, but GeForce doesn't offer that). If you're doing something with GPU computing or video encoding, my understanding is the second GPU can be piped in as a second worker - not to 'double the power' but to run a second job/task simultaneously.

Now, for the 'more on this later' - nVidia is officially ending SLI (on all platforms) this year, if they haven't already (I forget if the target was Jan or Feb '21), so apart from historic curiosity it's fully dead even if you switch to Windows, unless you use outdated drivers. The last time I booted Ubuntu up on my QuadSLI-equipped machine (which was 20.04 if I'm remembering right, running relatively new nVidia drivers (440 I believe)), all four GPUs showed up for compute, but none of the 'enable SLI' commands had any effect, and none of the options in the driver CP existed as various outdated guides will show, so my guess/understanding is that nVidia deprecated it on linux ealier than on Windows, and largely for the same reasons (almost zero customer buy-in).

As far as playing Skyrim itself goes - the GTX 690 is very basically 2x GTX 680 on one card, and GTX 680 is fast enough to handle that game (and then some - the system requirements call for a 512MB DirectX 9 GPU), so only using 'half' of the 690 (1 GPU) should still be entirely playable. That said, GTX 690 is a bit dated in terms of its I/O - like it has no HDMI 2.0, older DP outputs, etc - so if you need connectivity to a newer monitor an upgrade may be needed (GTX 900 series+ would get you HDMI 2.0 and better support for 4K (and beyond) outputs, or from AMD the RX 400 series or above). How are you running Skyrim within Ubuntu? That may have some bearing on performance/stability/etc

I will also say I would stick with Ubuntu (or a derivative, like Xubuntu, Kubuntu, etc) if you want to stick with the nVidia card - I've had consistently excellent experiences getting the nVidia Proprietary driver to work there, so that's 'good.' Changing distros won't change that SLI is A) fully deprecated (or will be soon) and B) badly/not really supported in linux for some time.

obobskivich - Thank you! I understand. In fact, the game looks good (it's SkyrimSE not 'Oldrim' - Oldrim performs much better). However, I do get freezing and stutters sometimes and the fps drops alarmingly.

Thanks to a command in the article TorC mentions, I can see that Ubuntu does 'know' there are two cards but I'm unclear how the second is being used. I saw some one degree temperature fluctuations yesterday which I hadn't seen before but that isn't much by way of proof. I've tried watching FPS as well but that's inconclusive. Neither do I know if there are really two totally separate cards - I still have to open the box and look. However, I can give up on SLI and I know it isn't me. It now makes sense. The latest driver presumably has got rid of most ways of manipulating SLI hence the 'on' command isn't recognised. It does - as I say - support mosaic but I don't want to run two monitors.

I run SkyrimSE via Steam but my guess is that the mods I'm using are making unreasonable demands...

As for Ubuntu - I run Mint with Cinnamon on another machine and were I starting out maybe I'd have started with that but I really really like Ubuntu and Gnome so the change wouldn't have been done lightly. I do have an HDMI monitor but have been unable to get the audio to be reliable without 'killing' pulseaudio. Skyrim would suddenly become soundless so I've resorted to external speakers. I don't think more experiments with HDMI on my set up are on the agenda yet. Sound in SkyrimSE has been an issue on Linux since we first could play via Steam and that's down to how it was implemented in SkyrimSE.

I'll wait patiently (!) for TESVI by which time hopefully the computer manufacturers in the UK will be rather more Linux friendly than they are and I'd likely stick to Nvidia because at least they've had a stab at supporting Linux. The Linux bit is non-negotiable even if Bethesda do the unthinkable and make TES VI impossible for me to run. I have no intention to buy things from manufacturers if they insist on ignoring Linux and try to reinforce Windows. I've really had enough of that! I may just game now but once computers were a huge part of my working life.

But thank you so very very much for explaining so clearly what I've struggled to understand via searches elsewhere!:)