1080ti SLI in VR


#42

Well, you said you don’t see how SLI would increase the sharpness in any game. AA above factor 1.0 is very demanding on the GPU as it effectively has the GPU render the frame in a higher resolution than the output resolution will be, and many people currently are limited by their GPU in the ability to increase the AA factor beyond say 1.5 - 2.0. So if you get another XX% of GPU power, you can go beyond such values and get a -perceived- sharper image. That’s why SLI would be one option to increase sharpness - if you already have an over-clocked Titan or 1080Ti, there is no option to increase the GPU performance other than SLI.


#43

What you are saying is supersample improves sharpness.
And sli helps to get more performance for that.

My reply was to the comment where no supersample was used and just simply going SLi.

I did say unless you change the resolution is running.

But I get what you saying


#44

Well they did sell it as a new game price. (Milking consumers for a vr patch job)


#45

There is no real benefit from SLI/CF VR until one GPU per eye. That will be only true multiple GPU support with benefit.
For that, we should wait even there is already technical possibility to implement that in DX 12 and Vulcan and by newer generations GPU.
This need to be implemented by game developers side as well.

Theoretically, we got it, practically we don’t.


#46

True there even saying really multi-gpu is not really sli/cf but affinity masking i think they called it.

As sli/cf use alternate frame rendering; where as you said vrwerks & liquidvr is about gpu(s) per eye to create 1 frame.


#47

There is a forum thread
https://forums.geforce.com/default/topic/981472/vr-general-discussion/-vr-sli-vr-sli-supported-games-list/
on Nvidia for known supported Games (unoffical) for the


support. So if you know a game, might be worth to add it or have a list here on the 8K Forum - I guess we will “need” SLI Support for the best experience.

I would love to see more games support this, it seems a good way to boost the FPS in VR - Maybe PiMax and Nvidia and Unreal / Unity should get something started ( @xunshu ).

I guess no matter if its a 1080ti SLI or will be a 1180TI SLI - just a side note with out a link, the newer the card the better the VR SLI support afaik (obvious).

Edit: I dont have real world SLI experience - that could change :wink:


#48

i have not jumped on the SLI or crossfire train for various reasons. First of all I actually never „seriously“ needed the extra performance and even with my previous RX580 i was able to play most games (with a little options tweaking) in 4k between 42-75 fps which was suitable for my freesync monitor. My recent 1080ti just laughes at anything in 4k at least suiting my monitors range 75Hz. So freesync with a nvidia card is not a loss for now.
I‘m very sensitive to frame rate changes and I read a lot about microstutters which seem still to be an issue. Many reports look that is not a myth. I definitly prefer little less resolution over less smooth motion. Any reliable sources that say that microstutters are not an issue anymore or that is has been fixed to a reasonable level? As I said I‘m very sensitive to motion interruption and I tweak EVERY game to be a steady as possible.


#49

No one asked so i have to do it: how do you mesured the sli-performance (ideally the gpu-usage via afterburner or other monitoring tools)? Thanks in advance.


#50

I would say SLI in VR would be a big thing, if support is properly implemented into game engines. Today’s GPUs are already underpowered, eye tracking and foveated rendering seems to be far away, and games are already suffering low frame rates on 1080Ti unless motion reprojection is used.

I remember having 2x980Ti. It actually worked way over expectations in most (non vr) games I played. Fallout 4 went from 35-40fps at 4K to mostly stable 60. The scaling of the second gpu was really not bad at all, and could mostly hit 90/80 or even 98/95 in some tiitles like ROTR.

Im not encouraged to buy another 1080Ti or two 1180, but if VR SLI becomes reality and if thats whats required to get full & stable framerate, then I would prefer it much more than foveated rendering.

Im afraid it will never happen though…


#51

I am stubborn- or more poetic “I keep having more dreams then reality can kill” so I Belive it will come - we just have to be the stone to raise the VR SLI Wave :ocean: ! Encouraging Developers, NVIDIA and PiMax to get it rolling-


#52

I think the upcoming headsets may “encourage” both devs and nvidia. Especially as none of the existing GPUs will hold up the framerate…

I may be wrong here, but for enthusiast market, I dont see foveated rendering as a solution. Its a workaround. But its also working against the whole purpose of wide FOV headsets that may become a standard in near future. Having a low resolution or blurry image in peripherals or where your pupils are not focusing feels like a big no-no to me…


#53

As I said I played almost any (non-vr) game even with rx580 on at 4k. only big map games like gta 5 online i had to turn down to 3k. offline worked fine at 4k.
Since I always need the game to be steady I put at least half an hour into every game playing with the settings and benchmark it. I figured that there are always at least two very neglectable options if turnend to low or even off will make space for much more headroom. I think that if a game struggles with the 1080ti the issues are with the game and not with the card at least as of yet. I have not played Fallout yet, but does it look sooo much better than games that have no major performance issues? or is it simply because unecessary big map parts are preloaded at once?


#54

Fallout 4 is an exception as its also very CPU and RAM dependent. But anyhow, running VR at high resolution and the problems within, has not much to do with in-game settings.

Once u go high resolution at framerates way above 60fps on TWO panels at the same time as we do in VR, then you will no longer benefit much performance by simply disabling some in-game setting or feature. The GPU still needs to render a certain amount of pixels to two panels. That needs high clocks. Thats a challenge, and as long as GPUs doesn’t get much higher clocks and more shader cores, nothing will help.

Also you need to remember for VR you are always rendering a much higher resolution than the native screen panels. Just because screens are 2560x1440p doesnt mean you are rendering the same resolution. Its way above that. And remember, we talk about two panels, PLUS a mirror view. In 80-90fps.

As an example, Vive Pro resolution is 1440x1600p per eye. What SteamVR renders to the Vive Pro at SS 1.0 is 2016 x 2240 per eye. Mainly because of the way it projects the distorted image onto the panel and corrects it. So to maintain good sharpness throughout the visible panel area, the total rendered resolution is higher from start. Now think about it. Pimax is 2560x1440p input…


#55

@SweViver thx for the clarification, that makes sense and I have not thought of it like that. But is it right to assume that most VR games simply lack of detailed settings (like mobile games) compared to regular games? At least I have noticed that the display/graphics configuration possibilities are very basic. just for example certain settings for lets say explosions are nice to have but in some games you will admire it once and then never look that closely again (certain extra textures on eg. guts like KF)
but are very demanding. would it not be a good way to ask the game devs to make their vr games more tweakable like we are used to? even if the rendering in vr is a demanding bitch, every frame counts in the end


#56

It depends on the game you play. Gorn doesn’t have any graphic option. Project cars 2 have the same graphic options on VR as normal one have. But it doesn’t mean the game is easy on GPU… And on anycase you don’t want to play it with everything low in VR, it’s too ugly.
Maybe on few years, it will be possible to play VR on low, but for now it’s too important to have at least high resolution, so we need a strong GPU…


#57

I already pointed out that I was not talking resolution. sometimes it‘s just cute but not really necessary effects that steal a lot of performance. We will probably need less antialiasing on higher rez for example on my 4k screen antialiasing makes little to no difference and it‘s a huge performance boost turning it off. Or reflections on water, yes I‘ll notice it once but I usually don‘t stay close to the water and admire the reflection each time I pass it. Also yes, Res. is the biggest performance hit but if you count all the fancy bullcrap a lot can be gained.


#58

Unfortunately, it depends on the game and your tolerance for ugly crawling stairsteps. In Elite Dangerous, even at 4K res, I find the lack of proper anti-aliasing to be HIGHLY OBJECTIONABLE. The only solution seem to be to run it at 2x super-sampling, which only reduces the ugly stairsteps and seriously reduces my framerate.


#59

It seems like you may be missing something with regards to foveated rendering. The whole reason that it is so sought after is that it provides huge performance gains with negligible effects on the user experience.

The only high resolution part of the eye is the fovea. Everything else has pretty low resolution and would typically be more attuned to motion sensing. There isn’t much point in rendering more detail than you can actually detect, so you can save a lot of rendering power if you only provide the detail where it is needed.

If your eye tracking and rendering are fast enough to race your eyes, then you can experience the same level of detail while rendering considerably less. A similar idea is how modern engines will generally only render details visible to the user. No point in working on something the user can’t see.

Links:
Fovea
Doc-Ok article - section on foveated rendering


#60

have not played ED as of yet so I can‘t rule out exceptions, but for almost any non-vr game in my steam library. Maybe we can agree on that the bigger the resolution at least the lesser antialiasing is needed which was basically my point.


#61

Well it all adds up to 1180ti SLI VR - sorry to repeat my self but I belive VR especially is perfect for SLI - a card per eye (screen) seems very reasonable to me and what SLI or CF can/could do.
We should start a petition or challenge Unreal/ Unity Engine devs and NVIDIA/ AMD to a Demo what cards and engines can do in VR.
Just need to figure about how …