Nvidia 1080 FTW Hybrid SLI in VR + flyinsidefsx - performs same as single card?

[theskyisthelimit 48]

This is my first shot at testing out SLI, ever..so i may be missing things here.

 

I have two Nvidia Hybrid FTW's in SLI.. i used the asus sli ribbon cables, both of them, to sli the setup.

 

In Nvidia control panel it says SLI mode.

 

I first tested 2D P3D, no change in performance there, but that was expected.

Then i tried flyinsideFSX and P3D.. same exact performance.. Flyinside reports sli is enabled.

 

I see the same 23-25 fps with 3 layers of thick clouds + rain + ut2 traffic + xpoi airports enabled in VR that i did before, nothing has changed.

 

 

Is there perhaps some NI settings that need set, or something else I may be missing.

 

I knew there would probably be no gains in P3D 2D, but VR i expected differently.

 

This on the z170-a asus board.

 

Thanks in advance

 

 

 

[glider1 90]

I see the same 23-25 fps with 3 layers of thick clouds + rain + ut2 traffic + xpoi airports enabled in VR that i did before, nothing has changed.

 

First thing is good news that the installation went well. Two 1080's in SLI is pretty special.

 

Problem is you are CPU limited. Even the cloud layers in AS2016 put a load on the CPU. The SLI of an already powerful GPU will only improve the performance of the goggles in VR. The best possible framerate you will ever see in your scenario as indicated by Flyinside will be 23/93.

 

First thing is to check that both GPU's are actually doing work.

 

Then try progressively turning on every single GPU heavy setting one by one until you see the 90fps indicator in Flyinside drop. Remember that the 23fps indicator won't change much if at all.

 

If after turning on every shadow in your test scenario, if flyinside is still showing 23/90, you can be pretty sure SLI is working. On a single non-sli 1080 in your above scenario, there is no way a 1080 could drive every shadow option at 90FPS.

 

You are possibly going to find that goggle performance in SLI might allow for just a few more graphics intensive options to be turned on. SLI won't double your performance unfortunately - no miracles.

 

Also pay close attention to the smoothness of panning. There is a way to test the smoothness empirically with the Oculus debug tools, but not sure how. Otherwise just quickly pan your head across the virtual cockpit of a complex aircraft and see if the panning is completely smooth.

[theskyisthelimit 48]

First thing is good news that the installation went well. Two 1080's in SLI is pretty special.

 

Problem is you are CPU limited. Even the cloud layers in AS2016 put a load on the CPU. The SLI of an already powerful GPU will only improve the performance of the goggles in VR. The best possible framerate you will ever see in your scenario as indicated by Flyinside will be 23/93.

 

First thing is to check that both GPU's are actually doing work.

 

Then try progressively turning on every single GPU heavy setting one by one until you see the 90fps indicator in Flyinside drop. Remember that the 23fps indicator won't change much if at all.

 

If after turning on every shadow in your test scenario, if flyinside is still showing 23/90, you can be pretty sure SLI is working. On a single non-sli 1080 in your above scenario, there is no way a 1080 could drive every shadow option at 90FPS.

 

You are possibly going to find that goggle performance in SLI might allow for just a few more graphics intensive options to be turned on. SLI won't double your performance unfortunately - no miracles.

 

Also pay close attention to the smoothness of panning. There is a way to test the smoothness empirically with the Oculus debug tools, but not sure how. Otherwise just quickly pan your head across the virtual cockpit of a complex aircraft and see if the panning is completely smooth.

 

I cranked up the shadows, even set sgss to 4x.. i guess the good news is, the fps dropped 1.5 and only 1.5.. at least on a quick test i did today.. 

 

Panning is still the same, with or without sli, for this saved flight, not the smoothest.

 

I wasnt sure if i needed to do any NI changes.

 

I also ran 3dmark.. it went from something like 5500 (off top of my head) to around 9700.. so clearly in that regard SLI is working.

[glider1 90]

I cranked up the shadows, even set sgss to 4x.. i guess the good news is, the fps dropped 1.5 and only 1.5.. at least on a quick test i did today..

 

That is good news. If it can hold 90fps with those settings, SLI is doing it's job nothing more can be expected. Disappointing that there is no change to smoothness of panning. I suspect that the smoothness depends on CPU as well as GPU. I have turned hyperthreading back on to try ensure the threading engine is working at it's most efficient hoping that will help with smoothness of panning in the virtual cockpit. The smoothness is very acceptable already, just looking to improve it that extra bit.

 

Thanks for the report on SLI, we already knew it would not be an FPS miracle, your results make sense. It allows more GPU options to be turned on without impacting current FPS too much. You SLI'd two 1080's, but if other SLI'd two lesser cards they might have more chance at sustaining the 90FPS goggle framerate.

[theskyisthelimit 48]

That is good news. If it can hold 90fps with those settings, SLI is doing it's job nothing more can be expected. Disappointing that there is no change to smoothness of panning. I suspect that the smoothness depends on CPU as well as GPU. I have turned hyperthreading back on to try ensure the threading engine is working at it's most efficient hoping that will help with smoothness of panning in the virtual cockpit. The smoothness is very acceptable already, just looking to improve it that extra bit.

 

Thanks for the report on SLI, we already knew it would not be an FPS miracle, your results make sense. It allows more GPU options to be turned on without impacting current FPS too much. You SLI'd two 1080's, but if other SLI'd two lesser cards they might have more chance at sustaining the 90FPS goggle framerate.

 

Yeah i guess this was expected.. i just wish i could get about 5 more fps in my "worst case" scenarios like this.

 

I also should retest with these "higher" settings with a single card just to verify that the i get MORE than a 1.5 fps drop in performance.

 

I'm wondering if maybe there is a benefit to taking off the SLI.. putting the goggles on one card and the main screens on the other.. and then doing flyinside.. unsure if this would even work, but i thought maybe it would split the load, maybe enough to see an increase in FPS too.. a test i may try later (i have my doubts)..

 

Otherwise its a big price to pay just to turn on a few shadows and turn on SGSS, though SGSS is a bit of a nice thing to enable if its possible, even in VR land.

[glider1 90]

Otherwise its a big price to pay just to turn on a few shadows and turn on SGSS, though SGSS is a bit of a nice thing to enable if its possible, even in VR land

 

Yeah it is a lot of money in SLI for just a few improvements. There would be more improvements with lesser cards than a 1080 though.

 

I too need that extra 5 fps. With that, we could be sitting at 25fps worst case in any situation.

 

We want a CPU that can hit 5GHz+ ideally.

 

A 64 bit simulator would also do the job, but then we would have to wait for a long time until all the addons get updated.

[Slayer 190]

Wondering how much performance boost there would be in X-plane, have you tried the demo just to experiment?

[theskyisthelimit 48]

Wondering how much performance boost there would be in X-plane, have you tried the demo just to experiment?

I may try to test this if i get some time, i do have the full version, but honestly havent used it in ages..

 

Meanwhile.. i will post a full summary of my results here once i get past a few issues..  I posted the issues here in another thread.  (basically, i cant get flyinside to hook and launch suddenly, despite a reinstall of oculus as well.. and i'm trying to find a way to get 4SGSS to work without tanking the ATW fps on a single card, so as to avoid keeping the second card.. seems to be the biggest advantage and visually it does help).

[theskyisthelimit 48]

I may try to test this if i get some time, i do have the full version, but honestly havent used it in ages..

 

Meanwhile.. i will post a full summary of my results here once i get past a few issues..  I posted the issues here in another thread.  (basically, i cant get flyinside to hook and launch suddenly, despite a reinstall of oculus as well.. and i'm trying to find a way to get 4SGSS to work without tanking the ATW fps on a single card, so as to avoid keeping the second card.. seems to be the biggest advantage and visually it does help).

 

Biggest issue, now that i have things semi working again is..

 

Flight1 GTN seems to break things, cause 5 fps.. seems to be related to the gtn windows that open and i cant close them all the time.

 

Also, the pan stutter issue i have with SLI enabled is still present.

[theskyisthelimit 48]

Someone in the flyinsidefsx side of things seemed to indicate that VR and flyinsidefsx dont mix.. leading to latency and other issues (and maybe the pan stuttering)?

 

I disabled sli, it didnt fix the stuttering however.. removing that second card did though.

 

I just cant hit 90 ATW with 4 SGSS and a single card.

[theskyisthelimit 48]

Here were my official results (i've since gone back to a single card, since i couldnt figure out why i get pan stuttering with SLI/2nd card in place.. i guess because sli + VR isnt a good mix as of now)..

 

In all of these, the GPU is not overclocked in any way.  Ram at 3466 mhz / 4.7 ghz cpu.

 

 

Scenario:  chicago midway addon with chicago X with 3 cloud layers and rain (GEX, UTX, REX, ASCA, UT2, XPOI airport names only)

 

Test1: SLI ON, SGSS 4x ON, UT2 running with XPOI   FPS:   21 / 90  (but,  i am getting head panning stuttering )

Test2: SLI ON, SGSS OFF, UT2 running with XPOI  FPS:  22 / 90 (still head pan stuttering)

Test3:  SLI ON:   SGSS ON, ut2 running w/ XPOI *rain off/fair weather on:   FPS:  23/ 90    (head pan stuttering)

 

These below were done after I removed the second card.. The fps were the same when I left the card in but had sli disabled, but I was still getting stuttering on panning, I did not get stuttering when I removed the second card:

Test4: SLI OFF:  SGSS ON, ut2 running with XPOI:       FPS:  22 / 50-56**   (so the VR fps astw rate suffers)

Test5:  SLI OFF:  SGSS off, UT2 running with xpoi:    FPS:  23 / 90

Test3:  SLI OFF:   SGSS off, ut2 running w/ XPOI *rain off/fair weather:     FPS:  23/ 90  **Same frame rate as with rain! 

 

*With XPOI off, the frame rate stayed the same, probably because I only show airports

 

**NYC X testing in p92 eaglet, fair weather unless noted

Test6: SLI OFF:  SGSS OFF, ut2 running w xpoi:   FPS 45/90+

Test7: Sli off: sgss off, UT2 running w xpoi and 3 layers clouds / rain:   FPS:  36 / 90

Test8:  SLi off:  SGSS ON 4x, ut2, xpoi, fair weather:   FPS:  43 / 55-85 ** (VR fps astw rate suffers)

Test9:  SLi off:  SGSS ON 2x, ut2, xpoi, fair weather:   FPS:  46 / 70-93

Test10:  SLi off:  SGSS ON 2x, ut2, xpoi, rain and clouds:   FPS:  40 / 55-65** (VR fps astw rate suffers)

Test11:  SLi off:  SGSS OFF, *ut2 off, *xpoi off, rain and clouds:   FPS:  46-50 /93

 

So 2x works ok until rain is added to the mix (with a single card).

 

I found that trying 8x (with no NI profile) for MSAA in the sim made little difference in terms of shimmering.. what i've now gone to is setting Antialiasing to Enhance and transparency supersampling to 4x supersampling for now, with MSAA in sim matching at 4x.. NYCx which is very prone to shimmering gets reduced somewhat, less ground shimmering, less building top shimmering (UTX buildings).. still present but not as bad.. 

[Mickeyj 35]

Hi,

 

im not on VR atm but concerning your scenario try to disable US Cities Chicago X i encounter bad stutters with Chicago X on a single GTX 1080 with and without FSDT KORD and/or ORBX Meigs Field.

[theskyisthelimit 48]

Hi,

 

im not on VR atm but concerning your scenario try to disable US Cities Chicago X i encounter bad stutters with Chicago X on a single GTX 1080 with and without FSDT KORD and/or ORBX Meigs Field.

 

That might help with the conflict with midway, but i may try to disable some bgls from chicago x as well.. the stuttering on panning though, that i think was the SLI situation..

 

I'm seeing there is new support from Nvidia for per eye gpu (vrworks i think its called) but it comes from the rendering engine and isnt fully supported out there yet..

 

I also now realize i think i needed the $39 0 slot HB link adapter rather than the ribbon.. i had two ribbons on, i think only 1 was really working.. to get the extra bandwidth it requires one of these sli link adapters.. i have one coming.. i'm going to retest and see if the pan stuttering goes away or the fps go up.

[glider1 90]

. i have one coming.. i'm going to retest and see if the pan stuttering goes away or the fps go up

 

Yeah it makes sense to improve the SLI bridge. To be honest, the whole SLI design is pretty bad. We shouldn't need to bridge the two cards at all, it should be built into the motherboard but we have to live with a band aid solution to piggy backing GPU's in SLI.

 

The bridge might help speed the two GPU's communicating with each. It could help with stutter if the stutter is a GPU problem. If it is a CPU problem it won't help at all. It will not help give you more simulator fps because you are CPU limited on that.

 

I have a suspicion that the panning stutter across the virtual cockpit is a problem with CPU threading and won't be fixed by SLI. Let's hope I'm wrong.

 

On my end, the panning stutter is really only a very minor annoyance on a single 1080, but I don't fly heavies. Some people get it, others don't.

[theskyisthelimit 48]

Yeah it makes sense to improve the SLI bridge. To be honest, the whole SLI design is pretty bad. We shouldn't need to bridge the two cards at all, it should be built into the motherboard but we have to live with a band aid solution to piggy backing GPU's in SLI.

 

The bridge might help speed the two GPU's communicating with each. It could help with stutter if the stutter is a GPU problem. If it is a CPU problem it won't help at all. It will not help give you more simulator fps because you are CPU limited on that.

 

I have a suspicion that the panning stutter across the virtual cockpit is a problem with CPU threading and won't be fixed by SLI. Let's hope I'm wrong.

 

On my end, the panning stutter is really only a very minor annoyance on a single 1080, but I don't fly heavies. Some people get it, others don't.

 

True, they do make it more difficult.. 

 

The pan stuttering was only when a second card was in there (and sli disabled) or with SLI on.. no pan stuttering otherwise..

 

however..

Suddenly tonight, back to single card.. i'm experiencing micro stutters when looking out the left window mainly.. like an eye twitch almost.. quite annoying.. tried going back to the default scenery.cfg .. no joy.. had it recreate the prepar3d.cfg file.. no joy.. reinstalled flyinside again.. no joy..

 

majorly frustrated.. its only when using the goggles as far as i can see.  (side offtopic note.. cranked up aerofly fs2, flying above kfso.. no stutters and the visuals amazed me.. so much crisper than p3d in its current state of vr, however, the plethora of content for p3d cant compare).