SLI with 2.5 Caucasus

[paradox64]

I'm pretty sure i had it one time without sli. I don't find too. It start when i recreate shaders but i put back the old one and same problem.

[Drag80]

So I checked on the CPU affinity thing in the task manager and all the Cpus are checked by default. So cpu bottleneck is not a problem. Sli is working absolutely fine. The only problem I have is that I have to press alt+enter once in the game to get sli to work. And if by mistake I press it once again then sli stops working and no matter how many times I press alt+enter again it doesnt work. Then I have to exit the game and load again.

 

This is a bit annoying. I dont understand the reason. Can Gsync or fast sync can have anything to do with it?

 

Or if there is a way that I can run DCS in true full screen mode by default ?

 

If anyone can help me out in this. That would be great.

[Drag80]

ok the alt enter problem is now solved. looks like the full screen option in dcs was unchecked. everything is good and sli is kicking a**.

:):lol::megalol::thumbup:

[paradox64]

ok the alt enter problem is now solved. looks like the full screen option in dcs was unchecked. everything is good and sli is kicking a**.

:):lol::megalol::thumbup:

 

aaaahh ok ! I didn't ask you because i was pretty sure you saw it lol

 

BUT

 

I also saw a thread somewhere who said that 2.5 is not a true fullscreen but a bordeless windowed mode due to game engine so i I thought you talk about this

 

sorry for my english lol

[paradox64]

Here's another thread on the cloud flickering:

 

https://forums.eagle.ru/showthread.php?p=3409280

 

I'm uncertain if it is SLI related or not. With earlier versions of DCSW, I would see flicker with the "old" clouds but I could fix it with vsync. Now, I only get flicker occasionally and only with the bottom of the clouds but vsync has no effect. But because it is intermittent, I'm having trouble finding a solution.

 

I finally found the answer for me ! I put it in the right tread but i'am now sure that it's because of the sli profil !

Edited February 26, 2018 by paradox64

[prccowboy]

I finally found the answer for me !

 

hmmm... that compatibility bit effectively turns off SLI on my rig. IF SLI is the reason for the flicker then that would fix it, but losing half my framerates doesn't work for me. I only see the cloud flicker occasionally anyway (I can't reliably replicate the problem). However, you have given me an idea and I will play with some other compatibility bits

[paradox64]

Are you sure it turn off sli ?... it's possible, i saw a very little loss of performance... i will take a look ! Thanks

 

edit: No it seems that this SLI profil don't shut off SLI for me (around 75-80% on each GPU) and also working good

Edited February 26, 2018 by paradox64

[prccowboy]

edit: No it seems that this SLI profil don't shut off SLI for me

 

hmmm.. are you using any other setting (like Forcing AFR2?) That setting drops my fps to single gpu performance levels. Anyway, I also replied to you on the other thread about a different setting to try (I wish I could reliably reproduce the flicker problem to make it easier to test for fixes)

[paradox64]

hmmm.. are you using any other setting (like Forcing AFR2?) That setting drops my fps to single gpu performance levels. Anyway, I also replied to you on the other thread about a different setting to try (I wish I could reliably reproduce the flicker problem to make it easier to test for fixes)

 

Here my settings :

[prccowboy]

I finally found the answer for me !

 

thanks Paradox, I will update my first post to show the latest info

[toutenglisse]

Sadly none of you guys seems to use VR.... Kind of test I would be very interested in ^^ (even if I read Sli would need a split frame rendering to be usefull with VR...)

[prccowboy]

Sadly none of you guys seems to use VR.... Kind of test I would be very interested

 

loan me your rig, I'll be happy to do some testing for you. I promise you will get it back... at some point ;)

[prccowboy]

Here my settings :

 

I saw from the other thread that you have switched over to the 0x080600F5 SLI compatibility bits like me but it looks like you might still be forcing AFR. I get better framerates with "AUTOSELECT" on all the SLI rendering mode settings (don't force AFR) with these bits - you may want to try that too.

[Drag80]

I would like to further add to this thread that according to the testing I did, using some sli bits put more strain on your gpu then required. The purpose is not to increase GPU usage, rather improve performance. The sli bits that I am currently using(settings posted earlier), put less strain on the GPU increasing their overclocking potential. However, the usage do increase when required, for example, I tested in normandy at most demading location and both GPUs went to 100% usage while the fps remained stable.

 

Both GPUs run stable at 2100 Mhz. When the usage increases at demanding areas, the temp increases and clock comes down to 2030 Mhz.

 

Although it required lot of hit and trial but I am happy that all of us were successful in using sli. At this graphic settings that I am using one 1070 was stuttering and flickering. Now two 1070s are giving super smooth gameplay.

[prccowboy]

SLI Setup

 

Since I started this thread, I felt compelled to write this post as a guide to others trying to get SLI to work in DCS2.5

 

Note: these settings work with the 2.5 Release build (2.5.0.15365.345); however, the 2.5.1 Open beta build may have reintroduced a cloud flicker problem ==> Update: flicker fixed in 2.5.3.21235

 

Configuring SLI:

 

DCS doesn’t have a working SLI profile from Nvidia. You will need to change the default profile to get SLI working properly.

 

First, make certain that you have SLI enabled in the Nvidia Control Panel. (3D Settings=>Configure SLI, Surround, PhysX=>Click “Maximize 3d performance” under SLI configuration)

 

 

Next, make sure that Nvidia Control Panel (NVCP) recognizes DCS (3D Settings=>Manage 3D settings=>Program Settings Tab=>Select a program to customize=>Digital Combat Simulator: Black Shark) Don’t worry about the “Black Shark” part, all versions of DCS use this profile. If NVCP doesn’t have this program listed, you will need to add it manually (“Add” then “Browse” to find the DCS program. Example: “F:>Program Files>Eagle Dynamics>DCS World>bin” and “DCS.exe”)

 

This will load the default Nvidia profile which does NOT work. You will need to change the profile.

 

 

To modify the profile, you need “NVIDIA Profile Inspector” by Orbmu2k (NVI)

 

Once you have started NVI, Select the “Digital Combat Simulator: Black Shark” profile. Next change the “SLI compatibility bits (DX10 + DX11) setting to “0x080600F5 (S.T.A.L.K.E.R.: Call of Pripyat)”. You may also have good results using other settings like “0x081000F5 (Dirt 3, Dirt Rally)” but some (myself included) have reported cloud flickering problems with those bits

 

 

The other SLI setting that you might need to change is the “Nvidia predefined SLI mode on DirectX 10”. I have best results (fps) with “AUTOSELECT” but others use “FORCE_AFR” or “FORCE_AFR2” (I also used AFR2 before 2.5)

 

 

Don't forget to click "Apply Settings"

 

Now SLI works in DCS, Enjoy the extra GPU power !

 

Note: In game, you might need to use L-Alt+Enter to switch to full screen exclusive while playing to see the full benefits.

 

 

Optimizing performance

 

Just because you now have SLI working and (theoretically) double the GPU power, it doesn’t mean that you will see FPS boost everywhere. CPU and GPU performance is related. To those thinking “my cpu utilization is less than 25% and/or I have affinity set to all cores, so I’m not cpu bottlenecked.” Well, you are probably wrong. It has been stated many times in other threads that DCS really only utilizes 2 cpu cores (with some additional threads being spread to other cores by Windows). If you have periods where your gpu utilization drops, then most likely one of your cpu cores just got maxed out (but the other cores are underutilized so overall it looks like your cpu is not the bottleneck).

 

 

In post #40, (here), I show how your framerates can be bottlenecked by either CPU or GPU:

 

There are some good guides to optimization: here, here, and here

 

However, I want to suggest that if your gpu’s show low utilization but you still want more FPS, try reducing “Visible Range.” This is one of the easiest ways to reduce CPU load and let it catch up to your GPU’s. In the end, I dropped my visible range and overclocked my CPU (but I know that’s not for everyone)

Edited September 7, 2018 by prccowboy

[Drag80]

Excellent guide prccowboy.

 

If u have already selected full screen in dcs system settings, you dont have press alt enter. Doing so will disengage sli and result in low fps and flickering. My recommendation would be to check the full screen option in dcs settings and once ganme is loaded dont press alt+enter again.

[paradox64]

I saw from the other thread that you have switched over to the 0x080600F5 SLI compatibility bits like me but it looks like you might still be forcing AFR. I get better framerates with "AUTOSELECT" on all the SLI rendering mode settings (don't force AFR) with these bits - you may want to try that too.

 

Yes I did ! Thanks and very good tutorial

[prccowboy]

you dont have press alt enter. Doing so will disengage sli and result in low fps and flickering.

 

I thought about this for awhile because it is inconsistent with what *should* happen. Some of the Nvidia Profile settings don't get fully applied unless you are in Full Screen Exclusive (ex: vsync settings), so maybe you have something in your nvidia profile which is causing the low fps and flickering when they get applied (by L-Alt+Enter)

 

Try checking your choice of SLI compatibility bits and your AA settings

 

This link suggests that MFAA is NOT compatible with SLI (and may cause flickering):

 

https://pcgamingwiki.com/wiki/NVIDIA_Profile_Inspector

[KoN]

I can get Sli working but not AA graphics look washed out and awful . Last patch has halved my frame rates . Does MFAA work with Sli does MFAA X 8 work . seems that no AA is working .

[prccowboy]

Does MFAA work with Sli does MFAA X 8 work . seems that no AA is working .

 

According to the link I posted earlier MFAA causes problems with SLI. You can try FXAA (which I use) or SMAA (with Reshade) with SLI. in-game MSAA also works but is costly in fps

Edited March 29, 2018 by prccowboy

[Sn8ke]

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.

 

I’ve tried every profile, setup, etc for years and will tell you this: Not only does SLI NOT improve your DCS performance, many developers including Nvidia have pretty much put SLI on the shelf. I’m not dismissing your work. I’ve been through the same thing. I’ve purchased two 1080 Ti’s and after tireless work, one of them is inside the box as a spare in case the other takes a dump. This research was done using DCS, Prepar3d V4, Ghost Recon, etc. Games are soooooo much smoother using one single X16 PCIE lane instead of two 8x PCIE lanes. I garuntee you with an SLI profile that works for you, if you go on the TGP, AI objects will flicker.

[paradox64]

I’ve tried every profile, setup, etc for years and will tell you this: Not only does SLI NOT improve your DCS performance, many developers including Nvidia have pretty much put SLI on the shelf. I’m not dismissing your work. I’ve been through the same thing. I’ve purchased two 1080 Ti’s and after tireless work, one of them is inside the box as a spare in case the other takes a dump. This research was done using DCS, Prepar3d V4, Ghost Recon, etc. Games are soooooo much smoother using one single X16 PCIE lane instead of two 8x PCIE lanes. I garuntee you with an SLI profile that works for you, if you go on the TGP, AI objects will flicker.

 

For having also made many and many tests and having doubts also, I am absolutely certain that the game is much more fluid in SLI than with a single card. I specify as I had already done above that I have 40 lines pci-e.

[prccowboy]

Not only does SLI NOT improve your DCS performance...

...one of them is inside the box as a spare.

 

"and yet it moves"

 

proof => HERE and HERE

[Sn8ke]

"and yet it moves"

 

proof => HERE and HERE

 

I will try it out.

[David OC]

I was researching vulkan api for VR benefits and as we know ED is implementing vulkan into there engine, now not to get anyone's hopes up. There is a chance down the track at some point that vulkan could help out here with more GPU's and not necessarily just in the SLI format possibly from what I can tell?

 

"The explicit multi-GPU set adds support for treating multiple GPUs as a single logical device, so that applications can easily make use of multiple GPUs in a single application for use cases such as Alternate Frame Rendering, Split Frame Rendering or VR SLI: "

 

New Sets of Extensions

 

I'm no programmer, still looks interesting.

Edited May 7, 2018 by David OC