SLI... question

hi.

I plan to buy 2 Nvidia pascal titan X. to do SLI.

I know DCS doesn't use SLI.

so when I want to play DCS can I turn off the SLI and just use 1 card.

(turn it off in the Nvidia control panel).

also. what percentage of people have a problem with SLI with their other games ?

5 % or 10 %

thanks

I used to have a SLI setup with two GTX 780 which I eventually upgraded to a 3-SLI setup before I went back to a single GPU setup.

If a game doesn't support SLI it will run automatically with on only one GPU, you don't have to turn it off yourself.

I will also add some of my experinces I had with SLI. Starting with the frustrating and negative things. First, there aren't many games that support SLI and if a new game gets released, the SLI support often lacks behind.

Than there is the point that many games, if they support SLI, will be bottlenecked by the CPU before they can use the GPUs to there full potential. I had an i7 4820K which was running at 4.6 GHz for that setup. The only game that used all 3 GTX 780 at ~100% was Witcher 3.

Next problem is the heat. For a two way SLI you want a Mainboard that offers enough space between the two graphic cards, so that the cooler of the upper card doesnt sit directly over the 2nd card. You can circumvent this problem by watercooling the graphic cards. Otherwise the GPU might hit the temperaturelimit and start to throttle down.

ANother problem is the increased input lag. Not sure if that is the correct term, but I will try to explain it. With each graphic card you add to the setup, the input lag increases. If you are playing FPS or 1st or 2nd WW planes, you will have to lead much further ahead of your target, because the image needs more time to be calculated and the target you see on the screen has already moved further ahead. I could test that quiet good with my 3 SLI setup, it was much easier to hit/lead a target with SLI turned off than with all 3 cards enabled. But if you play mainly singleplayer games and stick to modern jets, this won't be a game breaker. It was for me, when I was stilled playing alot of WT FRB/SB and IL2 BoS, which eventually made me change back to a single GPU setup.

Last big drawback, if you aren't single and have a girlfriend/wife, you will need either a good explanation or compensation for buying PC hardware for roughly 2400 bucks.

Good things is that you have more GPU power. I can also tell you, that the games I played with my SLI Setup which did support SLI, worked without problems. Especially Witcher 3 worked really good with all 3 GPUs.

Anoth good point is that you can use this setup as a good room heater (no joking), With all 3 GPUs running at 100% I could turn of my heater during winter.

Zettman

See my previous reply in the other thread just posted today about SLI... SLI absolutely works in 2.0.2.

Some games simply won't use both cards, and when you try and force it to run in AFR the game will crash. This is not so much a "problem" as forcing something that isn't supported and causing a game to crash. When you leave your nvidia profile settings at their defaults, SLI will not cause crashes or instability. It just might not use both cards.

http://forums.eagle.ru/showpost.php?p=2853213&postcount=6

To run graphically demanding games in UHD and at Ultra graphic settings and 60fps, SLI is mandatory. There isn't a single card out there which can deliver that level of performance. Even the 1080.

To run graphically demanding games in UHD and at Ultra graphic settings and 60fps, SLI is mandatory. There isn't a single card out there which can deliver that level of performance. Even the 1080.

On paper this is right, but in practice many games will be bottlenecked by the CPU before they hit the GPU limited, even with my 21:9 (3440x1440) UHD Monitor I was often limited by my CPU and not by my GPU. So SLI won't always help and nothing is more saddening than unused hardware imo. Even VR isn't using SLI/Crossfire if I'm still uptodate.

You are right in case of VR through, here my single GTX 1080 runs at ~100% if I turn the pixeldensity above 2.0.

But that depends on what the OP wants do do with his setup and as it was already said twice, he won't have a problem with games that don't support SLI, the will automatically just use one GPU.

Zettman

On paper this is right, but in practice many games will be bottlenecked by the CPU before they hit the GPU limited, even with my 21:9 (3440x1440) UHD Monitor I was often limited by my CPU and not by my GPU. So SLI won't always help and nothing is more saddening than unused hardware imo. Even VR isn't using SLI/Crossfire if I'm still uptodate.

 

You are right in case of VR through, here my single GTX 1080 runs at ~100% if I turn the pixeldensity above 2.0.

 

But that depends on what the OP wants do do with his setup and as it was already said twice, he won't have a problem with games that don't support SLI, the will automatically just use one GPU.

 

Zettman

This limit isn't theoretical. Try running something like Far Cry 4, Crysis 4 or any of the graphically demanding games. One GPUs will just not handle it.

For example if you wanted to run Battlefield Hardline at 3840x2160, a single GTX 1080 won't be enough to get a constant 60 FPS. SLI boosts that from 42 vs 79 FPS

http://www.guru3d.com/articles_pages/geforce_gtx_1080_2_way_sli_review,15.html

Flight sims will vary depending on the situation whether the bottleneck is the CPU or GPU. Scenarios with many objects, other aircraft etc will be capped by the CPU. Those with less objects are limited by the GPU.

In the CPU limited situation, the resolution 1080p vs 4K doesn't make any difference nor does adding a second graphics card. But real gameplay varies between those extremes.

hi socket 7.

you said= when you try and force it to run in AFR the game will crash

what does AFR mean ?

^ I believe he means Alternate Frame Rendering which is what SLI typically does. Each GPU renders an alternate frame. It can be forced through Nvidia Control Panel. I'm not sure what the advantage is and only ever tried it once but it actually seemed to work in that case where a game didn't seem to have full SLI support. Some games say "Custom" under SLI. I didn't experience any game crash.

^ I believe he means Alternate Frame Rendering which is what SLI typically does. Each GPU renders an alternate frame. It can be forced through Nvidia Control Panel. I'm not sure what the advantage is and only ever tried it once but it actually seemed to work in that case where a game didn't seem to have full SLI support. Some games say "Custom" under SLI. I didn't experience any game crash.

Indeed DCS 1.5.4 in my case supports SLI only if I force it to AFR2 mode via NVidia Control panel. No-go for SLI if any other mode is selected.

I ran some tests. Yes, DCS uses both GPUs although for me it's in a 99/25 split.

Selecting 1GPU in Nvidia CP makes no difference in this usage nor performance.

Turning off SLI was only possible by disabling it completely.

Test was the F-86 Free Flight mission.

Running 3840x2160 on all max settings I get an average frame rate of 84, SLI or No.

But I can tell the reason SLI isn't resulting in higher FPS it's because DCS performance is capped by the CPU regardless of your graphics card, if it's a strong one.

When I ran the same test track with the resolution reduced to 1080p, the frame rate only boosted to 88. So that's why SLI seems not to work. The bottleneck is the CPU.

Sharp, have u tried to set compatibility bits to "AssetoCorsa" for SLI? It works for the 368.69 driver but not 368.81.

No I haven't tried that game. DCS runs very well on it's default SLI settings for me.

What my test seems to reveal is that a single Titan X or 980Ti is enough to run this game in 4K

The situations of low frame rates are due to the CPU and so adding a second GPU won't help.

Another game I'm running right now is Homefront: Revolution. That type of graphics intensive shooter will run both GPUs at 99% It did not initially have SLI support and so didn't perform well, but that was added with a patch and now runs very well.

Sorry, gave the name assettocorsa because I didn't remember the specific numbers 0040000xx it stood for. This will even out gpu usage in Dcs.