DEFINITVE SLI / Xfire VS CV1 Thread, post your specs and experience...

[steveoz32]

Hi Chaps,

**EDIT** please read my latest post with regards to experience in SLI and surround. It does appear SLI with 'maximise 3d performance' does NOT utilise the second GPU in VR. However, if you are an eyefinity or surround user with multiple displays merged as one, GPU2 IS utilised and there is some odd behaviour ***




I haven't seen anything like this, so thought I would post up, and also thought it would be a good idea to keep this information in one thread.

I figured it would help those asking the question about SLI and VR and those looking to SLI and VR.

If we could just post CPU / GPUs and RAM it might help (PSU, storage, cooling etc all irrelevant). So I will start it off:

Processor: I7 4770k @ 4.2ghz boost
GPUS: GTX 780 AMPs
RAM: 16GB DDR3 @ 2133


System Compatibility:

Overall no issues, setup ran just fine and installed straight away.

I didn't even have to disable surround, I continued to run three monitors as one screen, plugged the rift into GPU one, it was detected and worked with zero issues out of the box. I was totally surprised.


EVE:

Setting = HIGH
For the best part, no lag or stutter with SLI enabled, upper mid GPU utilisation on both GPU (60-70%)
Solid 90 FPS
Maybe once or twice a round I will get a sudden stutter with head tracking, due to the low frequency of this, I can not say it is SLI specific

Lucky's Tale:

Setting = Highest
I have not experienced and lag or stutter at all with this title.
Solid 90 FPS
GPU utilisation around 60% on both cards.

UE4 Demo:

Solid 90 FPS, not stutter / tracking issues, GPU usage high 80's.


Elite Dangerous:

Playable on VR high settings, with high GPU usage on both.
90 FPS.
Stutter if moving away from high VR preset and supersampling or upping detail, FPS drops


House of the Dying Sun:

Crazy stutter in menu or prompts, oddly game pretty much works fine.
Lowest setting or maximum settings make zero difference to the stutter in menus
Game itself runs at 90 FPS, however can experience some stutter from time to time, not enough to make me feel sick or detract from the experience though.


Vanishing of Ethen Carter:

Smooth as butter on the high preset with maximum GPU usage on both cards.
90 FPS generally
FPS only seems to dip and experience monsterous stutter during the investigation (when the black and white effect comes up)


AltSpaceVR / Vtime / BigScreen Beta / Oculus Home / SteamVR

Smooth throughout really, none of theses are particularly taxing, so the experience is smooth.
The only exception is BigScreen Beta in multiplayer, there is quite a bit of stuttering and lag.
You can play games in windowed mode in BigScreen just fine, depends on how demanding the game is though as to whether you will get stutter. Same for Steam Theatre in Steam VR.


VR Movies / shorts in general:

No problems at all in Colosus, Henry, or any of the others all totally smooth with smooth tracking


3rd Party Apps:

Affected, VR model viewer, WaifuSexSimulator / MocuMocu dance, generally all good. Some demos I have tried have been terrible, but that is due to low utilisation and poor optimisation, not SLI specific. Depends totally on engine and optimisation.



It would be great if others could chime in.

I am especially interested in seeing what other SLI cards run well. I have been looking to uprgade to a 1080 Amp Extreme, however, getting tired of waiting for availability, and seeing how the 1080 is only 15% or there abouts more performance in a lot of current titles than a single 980TI, I am seriously tempted for the price to go from 780 SLI to 980TI SLI for £740 instead of paying the best part of 700 just for one 1080.

[pokabroma_bcn]

Maybe I'm misinformed, but I think right now, SLI & XFIRE are not compatible with VR, because of latency issues.

[steveoz32]

pokabroma_bcn said:

Maybe I'm misinformed, but I think right now, SLI & XFIRE are not compatible with VR, because of latency issues.

Did you not read my post? lol?

[FX2K]

CPU: i7 3970x
GPUS: 980ti SLI

Project Cars
I have to disable SLI otherwise its an absolute mess with tracking / double images and a down right puke-able experience 🙂  Completely unplayable.

Elite Dangerous
I experience an issue relating to planet lighting with SLI enabled, although this is not exclusive to VR.
Other than that, I notice no side effects of having SLI enabled, but I get solid 90 FPS with or without anyway.

[pokabroma_bcn]

Pardon me, I must have misread, because I don't speak english  very well. I did, and I didn't see anything about it. 

[steveoz32]

FX2K said:

CPU: i7 3970x
GPUS: 980ti SLI

Project Cars
I have to disable SLI otherwise its an absolute mess with tracking / double images and a down right puke-able experience 🙂  Completely unplayable.

Elite Dangerous
I experience an issue relating to planet lighting with SLI enabled, although this is not exclusive to VR.
Other than that, I notice no side effects of having SLI enabled, but I get solid 90 FPS with or without anyway.

Oh, it seems that PCars has the same issue as Assetto Corsa then, apart from it being a mess in general and terrible compatibility, it has this ghosting, almost a double image, you just saved me from getting that!

Interesting to hear about Elite too, although glad it is not SLI specific.

I forgot to add that in my original post:


Assetto Corsa:

Generally for 1.3 VR is a mess.
On the official forums there are many issues I have also experienced quite a few of these including:
Black screen / no display on rift, no loading, hard reset of the machine (these are not SLI specific)

If you can get it working it will NOT work with SLI. It has almost a double image with terrible ghosting, almost like a very low refresh rate oldschool monitor.

So steer clear of this if you are an SLI user.

[steveoz32]

pokabroma_bcn said:

Pardon me, I must have misread, because I don't speak english  very well. I did, and I didn't see anything about it. 

No problem, it is not officially supported, however there are a large number of SLI users in the general PC community. Lots of people have asked me outside of this forum. I thought it would be handy to have a thread about general compatibility and real life experience with such systems 🙂

[pokabroma_bcn]

Now I understand it better, Thank you for the additional explanation!

I think it's a very good idea, and I'm also waiting for SLI to work properly, then  I'll buy a 2nd card.

[Warbloke]

I just have a single 980TI,

I have Eve set to high and must say I find everything very responsive, no lag or s.. s... sss......stuttering.  The game plays very smooth Id say graphically wise.

Project Cars also is very smooth too.  I cant see what getting a second card would do for me. other than increase GPU fan noise.

[steveoz32]

Warbloke said:

I just have a single 980TI,

I have Eve set to high and must say I find everything very responsive, no lag or s.. s... sss......stuttering.  The game plays very smooth Id say graphically wise.

Project Cars also is very smooth too.  I cant see what getting a second card would do for me. other than increase GPU fan noise.

To be fair I was curious too not so long ago so disabled SLI, and to my surprise EVE ran at 90 FPS without the second card even being used, however GPU1 ramped up to 99% usage. So it doesn't seem it's really needed to run EVE. That said, I don't want to have to disable SLI / surround every time I run a game, hence leaving SLI enabled. It also appears to load the GPU's much less keeping temps down.

I don't think 980TI SLI would be worthwhile to you unless you have issues.

My problem is for surround gaming my 3GB VRAM is simply not enough to cut it any more. Games like the Division and Witcher 3 can not be run on three screens with a smooth experience. I also use between three to six screens so could do with the extra output on two cards instead of dropping some with the 1080.


Cheers!