SLI with 2.5 Caucasus

[prccowboy]

Does anybody have SLI working in 2.5 with Caucasus? <=This was my original question

 

edit (with latest findings):

 

SLI does WORK in 2.5, but: Ultimately your performance is either limited by your CPU or GPU. Think of it as 2 guys running a race but tied together by a rope. If one is slow, he limits the speed of the other. In DCS, when the CPU gets maxed out then the gpu becomes underutilized and vice versa.

 

Initially, I thought SLI wasn't working in 2.5 Caucasus because I was getting similar results with no sli (one gpu at 97% utilization) vs. SLI running (but both gpu's running below 50%). It turns out that one of my cpu cores was maxed so one videocard was enough to keep up with the cpu (and two cards was overkill). If I reduced cpu load but ran only one videocard then I still saw no improvement in fps (now my gpu was the bottleneck)

 

However, I now have my cpu maxed and both gpu's running SLI at about 98% utilization and see a huge improvement in performance (now my cpu doesn't slow down my video cards and vice versa)

 

I have written a guide to SLI setup (post #65) => HERE

Everybody has a different rig and will have different bottlenecks, but the point of this post is to confirm SLI does work but performance will vary if you have something else bottlenecking your framerates.

Edited February 27, 2018 by prccowboy

[b00ce]

I have 2 GTX-980s and I get 45-50 FPS in Georgia.

Not sure what my GPU utilization is though.

[prccowboy]

I have 2 GTX-980s and I get 45-50 FPS in Georgia.

Not sure what my GPU utilization is though.

 

Have you tried forcing SLI off and doing a comparison? My point is that I don't see any performance increase in Caucasus (in fact, performance drops) when using SLI. However, SLI does give me a boost in NTTR map

[Gladman]

Since when is SLI supported?

[TexasBread]

SLI does work if you force it through Nvidia Inspector. HOWEVER, you will get crap fps. With Sli I get abl it 45 fps. GPU utilization for both cards is about 50 percent. I have tried sli with AFR2 but no dice for better fps. With only one card i get 80-100 fps and 90 percent utilization. For the record I have two 1080ti.

[b00ce]

I had an approximately 10 FPS reduction when I turned SLI off.

[Gladman]

So again, its not supported and isn't worth considering at this time.

[prccowboy]

I had an approximately 10 FPS reduction when I turned SLI off.

 

b00ce, what compatibility bits are you using? driver?

 

 

So again, its not supported and isn't worth considering at this time.

 

I get a 75-90% boost in framerates with SLI on the Nevada map. I think that's worth consideration. This post is not a debate on whether SLI works in DCS, because it DOES (with profile tweaking). However, I would like to understand why it works with one terrain and not another for me.

[babypapa1]

For me, SLI Titan XP works definately in all three maps of 2.5 version. I'm getting 40% boost on average (near Batumi 50FPS vs 70FPS). I do NOT force SLI, instead I'm using DirtRally3 SLI profile (SLI compatibility DX10+DX11) everything else is default or NVIDIA recommended.

Edited February 4, 2018 by babypapa1

[Gladman]

Sorry Gents. I will choose to not believe you. I had an SLI setup and tried all the tricks people said would work and it did nothing. Until ED decides to implement it, your chasing ghosts.

[prccowboy]

For me, SLI Titan XP works definately in all three maps of 2.5 version. I'm getting 40% boost on average (near Batumi 50FPS vs 70FPS). I do NOT force SLI, instead I'm using DirtRally3 SLI profile (SLI compatibility DX10+DX11) everything else is default or NVIDIA recommended.

 

Thanks for the feedback BabyPapa. I took your message to mean that you use the default DCS:BS Nvidia profile and only change SLI compatibility DX10+DX11 bits to 0x081000F5 (Dirt 3, Dirt Rally).

 

I just tried that and hit the best fps I've ever seen in Nevada (about 100% boost); however, I still don't see any change in Caucasus terrain - Given the low gpu utilization that I'm seeing on that terrain, something else must be bottlenecking on my rig with that map.

[babypapa1]

Thanks for the feedback BabyPapa. I took your message to mean that you use the default DCS:BS Nvidia profile and only change SLI compatibility DX10+DX11 bits to 0x081000F5 (Dirt 3, Dirt Rally).

 

I just tried that and hit the best fps I've ever seen in Nevada (about 100% boost); however, I still don't see any change in Caucasus terrain - Given the low gpu utilization that I'm seeing on that terrain, something else must be bottlenecking on my rig with that map.

 

Did you press Alt-Enter at the beginning? My GPU usage in Caucasus map is usually around 70~90% in both cards. I guess if SLI works in Nevada, it should work in other two maps as well because they use a same graphic engine. Have you tried repair or fresh install?

[babypapa1]

Sorry Gents. I will choose to not believe you. I had an SLI setup and tried all the tricks people said would work and it did nothing. Until ED decides to implement it, your chasing ghosts.

 

Why don't you give it another shot? It is real and recently started to work.

[prccowboy]

Have you tried repair or fresh install?

 

Yes to Alt-Enter; clean and repair.

 

After more experimentation I have realized that it is NOT an SLI issue - The SLI is working but something related to visible range is bottlenecking my overall performance in Caucasus (such that in most conditions the SLI is running below 50% utilization)

 

If I drop the visible range setting (or change my view to limit the range) then I can get SLI gpu utilization up to 98% and I can see the SLI performance boost. (ex: Single gpu=60fps; SLI=100fps). I changed all other settings (texture level, tree visibility, etc.) and nothing else made a difference.

 

Whatever is causing this performance bottleneck for my rig, it's only in 2.5OB Caucasus. I don't see it in Nevada or 1.5 Caucasus.

[mhe]

So you can get SLI FPS gains from lowering the visible range? Sounds interesting, because so far I have been struggling with my SLI. Do you know whether the SLI advantage can also be gained when using cockpit software like Helios or Ikarus?

[CNETRO]

Hi, indeed, the use of SLI is not a big game changer, but I use it for the AA filter in SLI x8 to match the MSAA 8x.

[prccowboy]

So you can get SLI FPS gains from lowering the visible range?

 

not necessarily, but it seems to impact some other bottleneck that was throttling my gpu's in Caucasus. After running more tests, I have much better SLI performance gains in other areas of the map but something about my first test conditions @ Sukhumi killed my SLI performance.

 

 

Hi, indeed, the use of SLI is not a big game changer, but I use it for the AA filter in SLI x8 to match the MSAA 8x.

 

on Nevada, SLI is a *BIG* game changer for me under all conditions (about 100% improvement). Also, don't you basically disable SLI performance when you use SLI AA?

[CNETRO]

on Nevada, SLI is a *BIG* game changer for me under all conditions (about 100% improvement). Also, don't you basically disable SLI performance when you use SLI AA?

 

That is right, you cannot have both. But as far as I am concerned I have better performance in Caucasus, NTTR and Normandy with those settings.

 

Could you share your Nvidia's setting so that I can test them in my rig ?

 

B/R

[prccowboy]

Could you share your Nvidia's setting so that I can test them in my rig ?

 

I've used various profiles with success, but I'm currently using a slight derivative of BabyPapa1's suggestion above (only changing SLI compatibility bits DX10+DX11 and not forcing AFR2)

 

 

I also made a few changes for personal taste (set FXAA on and Vsync to Fast) but these changes are really more for quality preferences rather than pure performance.

[CNETRO]

I've used various profiles with success, but I'm currently using a slight derivative of BabyPapa1's suggestion above (only changing SLI compatibility bits DX10+DX11 and not forcing AFR2)

 

[ATTACH]178401[/ATTACH]

 

I also made a few changes for personal taste (set FXAA on and Vsync to Fast) but these changes are really more for quality preferences rather than pure performance.

 

Ok, thanks.

What Nvidia App are you using for those settings, because I am using the control panel, and I do not have those choises ?

 

@+

[prccowboy]

Ok, thanks.

What Nvidia App are you using for those settings, because I am using the control panel, and I do not have those choises ?

 

I use "Nvidia Profile Inspector" by Orbmu2k.

 

There is another thread in this forum about the app: https://forums.eagle.ru/showthread.php?t=202038

[CNETRO]

I use "Nvidia Profile Inspector" by Orbmu2k.

 

There is another thread in this forum about the app: https://forums.eagle.ru/showthread.php?t=202038

Hi,

Thanks, I will give it try.

But since the last fix, Nvidia's settings work really fine. (I came back to full SLI).

[Drag80]

Yday I installed 2.5. Sli does not seems to make a big performance boost. However, I Forced AFR2 in sli setting section. Today I will try with chaning ONLY the sli bits and keep everything else of default. Lets see how it workd out.

[prccowboy]

Yday I installed 2.5. Sli does not seems to make a big performance boost.

 

Yeah, try not forcing DX11 AFR2.

 

I discovered that under certain conditions my performance in 2.5 (especially in Caucasus) was being bottlenecked by my cpu getting maxed out - the video cards were being underutilized so that SLI wasn't making as much of a difference as 1.5/2.2. So, I dropped my visual range settings to reduce the overall load (while increasing MSAA because the gpu's were underutilized anyway)

 

I am happy with performance now - smooth with nice visuals (even in intense combat). I have a minor issue with occasional cloud flicker with SLI but otherwise all is good.

[Sn8ke]

I swore by SLI for years, however I just rocked a solid 60FPS all over Las Vegas in NTTR with high settings using a single 1080Ti. SLI has been causing texture flickering and other oddities like unusual stutters, etc. Going back to single card.