theskyisthelimit

SLI curiosity with p3d v4.1, gains in performance, all things held equal?

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Looking for some up to date info regarding any benefit of using SLI with P3D (and also XP11 in my case)..

The situation is that i'm testing triple 4K screens, insane yes.. frame rate can get pretty low.. 26 vs 45 for instance in P3d.. at least that low.. if i use surround mode its about this, but the warping is bad, so it seems the only way to do this is with windowed mode x 3 which kills it even more (unless i'm unaware of a better way)..

At any rate.. i have a single 1080 FTW Hybrid.. i was going to SLI another 1080 FTW (non hybrid if this even works) since i cant fit a second pump..

I thought at one point i read that there were no real performance gains from SLI, but with a triple screen setup, i would think there should be some.. maybe enough to go from 17-22 fps to 28 even?

Anyone gone through this and can share some inside info?  Any tweaks needed in NI, or just in the nvidia panel for performance mode or similar under SLI (i think).. (i had done SLI a year ago briefly but had no real boost, but I wasnt running triple 4k at the time)..

 

Thanks in advance

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Maybe this is not for you as i am not near a tri- 4K platform but SLI works great in P3Dv4.1. 

I have SLI GTX970´s and they do great in 4K and with heavy GPU demanding tasks.

Best for SLI is AA ,Resolution, Shadows  and overall image quality.

 

My own concern is the VRAM which is not doubled so i cannot use high resolution ground textures in heavy places

 

Thanks

Michael Moe

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I had 2 1080ti's in SLI. I saw very minimal performance gains. Only DX12 games really shined. Everything else was me flipping back and forth between CAM trying to see if my SLI was actually on which it was. But that tells you how little I was wowed. 

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11 minutes ago, tooting said:

To be honest the developers don't even know if there product is sli compatible... they couldn't be bothered to answer my question 

https://www.prepar3d.com/forum/viewtopic.php?f=6315&t=126826

They stated that P3D was SLI compatible years ago. They always recommend the default nvidia profile and they generally do not provide specific settings. I doubt you will ever get an answer.

When I was running SLI I just used the nvidia default for P3D - worked just fine with two 1070's. Problem is some people expect better FPS using SLI - that is not going to happen - smoother graphics yes but increased FPS no.

So set it up with the nvidia defaults, if you like it - fantastic - if not - you can try tweaking settings until you find a combo to your liking - but from a P3D standpoint - default nvidia P3D profile works just fine.

Vic

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I had sub-par performance with only 1 1070 Oclked.  Turn on SLI and the NVidia SLI indicator (NI) for an ingame representation.  Load looks even.

 

Cheers

bs

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Here's a question for those that did try it. Did you use an hb bridge not a ribbon. Apparently you lose 15%, but maybe only at 4k if you use the ribbons

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I used both and noticed no difference.

 

Vic

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I believe that Pete Dowson said he was using 3x 1080Ti in SLI for three 4K screens.  You might PM him over on his FSUIPC support forum.

I recently upgraded to a pair of 1080Ti in SLI (using the HB bridge that came with my ASUS Z270 motherboard).  I run 4K at 30Hz on a 55" TV.  I was using a pair of 980Ti GPUs in SLI, which I have now migrated to my gaming box (CoD WW2 rocks with them!).

After removing the 980Ti config, I started with a single 1080Ti.  Performance was pretty close to the same as the 980Ti SLI config, although some of the more aggressive AA configs actually seemed to work a bit better with the dual 980Ti config.  Based on what I saw there, I would have returned the 1080Ti and kept the 980Ti SLI config.  But then I added the second 1080Ti.  Performance in heavy weather with 4xSSAA was good enough to keep the frame rate pegged at 30.  In very demanding scenarios--e.g. dynamic lighting + SSAA + fog/overcast + 4096 textures, the 1080Ti SLI config kept up where the other two configs did not.  So when we talk about "increased performance" I measure that in the ability to hold stable frame rates, with smooth video.  If your idea of "increased performance" is simply higher frame rates, I can't answer for that...for me, anything over 30 is only manifested by a lower GPU load, which allows more headroom for peaks. 

The majority of the situations where I can induce stutters now are pretty clearly tied to CPU saturation, for example very high autogen settings together with a CPU-intensive add-on like the FSL Scarebus.  Is SLI it worth it--to me, yes, it means smooth and stable across a very wide variety of operating conditions without having to manage the config.  I still have separate day/night configs to widen that headroom as much as possible...for example heavy autogen and night flying don't make a lot of sense, and dynamic lighting and ORBX lights on in daytime flights don't either.  But I don't have to worry about taking a PMDG or FSL add-on into heavy weather, or about turning on the lights at night.  It's ugly expensive...yes...but then again so is a set of the Calloway golf clubs that some of my friends go out and buy.  You can make do just fine with less...less money, less hassle, less heat, etc etc.  But does it help get closer to Nirvana--yes.

Regards

 

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6 hours ago, w6kd said:

I believe that Pete Dowson said he was using 3x 1080Ti in SLI for three 4K screens.  You might PM him over on his FSUIPC support forum.

for example heavy autogen and night flying don't make a lot of sense, and dynamic lighting and ORBX lights on in daytime flights don't either.  But I don't have to worry about taking a PMDG or FSL add-on into heavy weather, or about turning on the lights at night.  It's ugly expensive...yes...but then again so is a set of the Calloway golf clubs that some of my friends go out and buy.  You can make do just fine with less...less money, less hassle, less heat, etc etc.  But does it help get closer to Nirvana--yes.

 

Thanks, ill have to give him a message and find out.  I'm curious in general how some of these folks are doing 3 screens with their home built cockpits.  I tried to go 1080 and it was pretty awful looking (on a 4k screen).  Actually, i'm more curious in p3d, i assume most are just undocking 2nd and 3rd views and making them into big windows, which dont perform as well as full screen.. wondering if they just hide the task bar or is there another trick i'm unaware of.  Either way, surround mode warping is a no go for me at least, but the frames were slightly better.

Curious, you mentioned turning off orbx lights.. side question but are you using the toggle start menu choice, because i tested that and it didnt work (i use Black Marble so having them off was more ideal)... the only way i've found is to turn off the bgl files in the root scenery folder, but then some orbx areas take 2 minutes longer to load, getting stuck on autogen loading at 80%.

I'm about to at least give up the current quest for triple 4ks.. i was looking at the 49" samsung thats out there, i think something along ultra wide that wouldnt require trackir would be the next best bet, but thats a $1500 bet right now (and there is VR, which i do use, but still hoping for better native "aerofly" like quality down the road).  My 43+ trackir might have to do for now.

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Any resolution other than native on a pixel-matrix type screen is going to be underwhelming I think...the interpolation that has to occur is never going to get it completely right.  Pete has a hardware cockpit and uses the screens for outside views only, IIRC.  I'm also not completely sure he uses 4K instead of 1080p, either.  I think you can do an outside-only triple with NV surround without the problems you describe.

I turn the ORBX lights on/off with a pair of utility executables that install with the ORBX software...something like ORBX_Lights_Day.exe and ORBX_Lights_Night.exe

Ever since I went with a 55" 4K TV (at ~35" viewing distance) I found myself not really wanting for more screen real estate.  Most of the multi-monitor solutions that give side angle views that I've seen have a lot of rectilinear distortion, unless you use some very pricey view-stitching hardware/software.  A 4-foot wide big screen right in front of my face is enough.  I am just now at the point where I can get the available hardware to keep that screen filled at a steady 30Hz...adding two more to the mix would take me right back to fighting for frames.

Regards

 

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@w6kd

Thats interesting, i didnt realize the outside (non cockpit) views didnt distort.. more than i can get into for now with hardware cockpits but that was good info thanks.

Yeah those are the exe's i tried for global lights toggling.. the before and after shots i took showed there was no change on my system for some reason, maybe ill revisit that and see if i goofed somehow.

Are you using trackir at all with the 55", id think there would still be a need for left and right views at 3840x2160 as opposed to some of the other wider angle options out there.  

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14 hours ago, theskyisthelimit said:

@w6kd

Thats interesting, i didnt realize the outside (non cockpit) views didnt distort.. more than i can get into for now with hardware cockpits but that was good info thanks.

Yeah those are the exe's i tried for global lights toggling.. the before and after shots i took showed there was no change on my system for some reason, maybe ill revisit that and see if i goofed somehow.

Are you using trackir at all with the 55", id think there would still be a need for left and right views at 3840x2160 as opposed to some of the other wider angle options out there.  

No, I'm not saying a VC outside-view only doesn't distort...I was addressing the severe frame rate loss with triple-wide in a regular VC.  The only way I know of to get unwarped side views is to use view-correction hardware/software (like fly-elise-ng).

No TrackIR.  I use a button on the yoke and a mouse, plus Opus view control and a Logitech G13 gamepad programmed to give me preset VC view pans (90 left, 45 left, fwd, fwd-hud, 45 right etc etc)...I have never been able to make TrackIR work naturally, or without giving myself a major neck-ache.

Regards

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