p3D + rift + SLI 1080 woes vs single 1080 SGSS4x performance

[theskyisthelimit99]

Curious if anyone else here is running dual 1080s or 980s for that matter and have compared having SGSS 4x on and off. I have my hands on a second 1080 and i've been evaluating whether i keep it for SLI or stick to single card mode?

I'm running into several issues.. first..

When i first put the second card in, i was experiencing horrific performance.. 12fps where in the heavy hitting chicago midway with rain i would be at 23 fps.. so i opted to remove and reinstall flyinside.. slightly better but this then caused more issues..

Now when i try to launch with ForceVRModeDev = 1 or from the flyinside exe itself.. it doesnt go to vr mode, just standard 2D.. so at this moment i'm removing oculus and reinstalling, unsure whats causing this..

I also kept getting p3d crashes on launch related to d3d11.dll which seems to show it coming from the c:\windows\system32\d3d11.dll path (there is also one in the p3d root folder).
I copied the file from the sys32 to the root of the p3d install and now its better so far, but i still couldnt get rift to fire up with flyinside (hence removing oculus).

I should also mention i did a clean driver install (eventually) with all this and it didnt help (nvidia)


Secondarily to all this.. has anyone compared 4SGSS with no SGSS in NI?
To me, i think the difference is substantial enough.

So far, the only difference i see, between single card and SLI mode, seems to be the SGSS.. if i turn SGSS to 4x on a single card.. it tanks the ATW frame rate .. so 23/90 becomes something like 23/60.
When i go SLI, that 60 goes back to 90.. the base sim frame rate does not change, nor is it really affected by turning on full shadows etc either with SLI ( cept maybe 1.5 - 2 fps difference with the sim rate).

So my other question is.. is there some magic setting that may allow me to set 4SGSS with a single 1080 and not tank the ATW?

Thanks in advance with this..

[theskyisthelimit99]

It appears that flyinside must install the d3d11.dll and 2 other dx related dlls.. apparently something got mangled during my many uninstall/reinstall attempts... as a result everytime i would try to launch p3d even without flyinside active, it would crash with an error related to one of these dll's...

I've since gotten past this and back to testing again, but the other curiosities remain.

I'm still having the issue of very poor VR performance however, which i think is only cured by using a clean install of flyinsidefsx.. still testing

[theskyisthelimit99]

The biggest issue i'm also having right now, with SLI enabled, in the pan stutter.. turn off SLI and i dont seem to have the issue.

Also the Flight1 GTN gps panel seems to break performance (it didnt before, suddenly it does).. seems related to the secondary windows it opens.. i could close them before or leave em alone didnt matter, now it does and i cant always get them to close.

[theskyisthelimit99]

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.

[frankbicknell]

Just set up 2 1070s with the SLI HB Link Adapter and all is well here.

[theskyisthelimit99]

Just set up 2 1070s with the SLI HB Link Adapter and all is well here.

Did you get a big boost from a single card as far as sim frame rate goes.. with that hb link adapter? I'm now facing micro side view stuttering i cant figure out, clean image and all too, wasnt present a week ago. Trying to sort this before the hb adapter gets here to retest SLI

[miaig]

I have 2x980ti and I have the same performance issues with SLI enabled. I need to disable it for FlyInside (and a couple of other VR games).

[theskyisthelimit99]

I received the SLI HB Evga adapter today.. short story is, no change, didnt help with head turning/panning stuttering.. neither does frame rate lock at any level.

Also.. when you use SLI + 4SGSS + rain (at least rain / clouds), the sim frame rate stays the same, but the ATW drops to 30-40! yikes.
So as of this writing it appears the 1080 SLI idea is a no go.. will just have to live with no SGSS and semi low frame rate in some areas with 3 layers of clouds + rain (18-25 fps worst case).


Tests:

**Near KORS with FTX PNW (again with GEX, UTX, REX, UT2).. with 3 layers of clouds + rain.. in bonanza 36..

NON SLI: Lock frames at 48 with ut2 active: 30ish / 85-93 but then suddenly as flying it becomes 17/85-93 within one minute passing over water (unsure why, its NOT ut2 related)
SLI: Lock frames at 48 with ut2 active: 29/95 (higher ATW) then becomes 21/94 (pan stuttering)


NON SLI: lock frames at 48 (no ut2): 31-34 then 24-30 (ut2 costs about 3 fps at 70/30 mixture)
NON SLI: unlim (no ut2) : 38/ 77 then becomes 26/77 after 2 min
SLI: lock frames at 48 (with ut2) and WITH 4SGSS: 30/35 (big hit on ATW)



**chicago runway test with us cities active from before with rain PMDG 800:

NON SLI Unlimited with ut2: 23/80ish (no ut2 about 27/85)
SLI: UNLIM with ut2: 24/92 (great ATW but the head pan stutter)
NON SLI: lock 48 with ut2: 17/80-90 (no ut2 about 20/80)


**chicago runway test with Us cities turned off with rain/clouds PMDG 800

NON SLI: Unlimited, no ut2: 36/70 (gain about 9 fps by unchecking aersoft us cities x, possible mod of bgl possible too)
NON SLI: Locked 48, no ut2 28/70

**NYCX fair weather test with p92:

NON SLI: lock 48, NO ut2: 45/92
NON SLI: lock 48, with ut2: 37/92

*NYCX with rain in p92:

NON SLI: lock 48, NO ut2: 35/92
NON SLI: lock 48 with ut2: 46/92
**didnt do sli test here, either way, minimal hit with rain/clouds here

[Tony]

Even though SLI is supported I really think if the original devs of a game changed their coding and had true sli support things might be better. Have you tried any other games that claim to have full sli support to compare ?

Tony

[theskyisthelimit99]

Even though SLI is supported I really think if the original devs of a game changed their coding and had true sli support things might be better. Have you tried any other games that claim to have full sli support to compare ?

Tony

I havent tested any other games.. yeah i'm sure its a limitation within P3D that causes the pan stuttering and limited improvement.

I just wish there was a way to get 4SGSS working with the single card without taking the ATW hit that it creates.