About SLI and Quad SLI @ B6

[desastersoft]

Good Morning B6!

Just an easy Question: Is in the upcomming Patch SLI and Quad SLI still working as "Performance Break"?

For Explanation: I am Using 3 Systems. The Big one is i7 - 6 Core @ 6x4GHZ, 12 GB Tripple Channel DDR3 RAM, and 2x GF 590 GTX with together 6 GB Video DDR 5 RAM.

The second Main System is i7 - 4x3,5 GB, 16 GB DDR3 RAM Quad Channel with a GF 580 AMP Version GTX with 3GB DDR 5 RAM.

The effect is, the System Nr. 1 is with 90 AC in Combat at 25-35 FPS on High End Settings.

The much smaller System, Nr. 2 is with exact same Settings and same Mission at 50-120 FPS!

Oleg wrote me at beginning of CloD, before he was gone, that this belongs to the not implemented SLI and Quad SLI support.

Is this crazy feature still in? Or did you solve the Problem?

Cheers
Thomas/Chief of Desastersoft

[KeBrAnTo]

This is something quite a lot of people would like explained, indeed.

Still waiting here too ....

[Skoshi Tiger]

I thought that SLI worked independently from the application programs. Is there a SLI API or list of guidelines SLI optimisation for developers? If so where?

[RickRuski]

I'm am too quite curious about the situation with Sli. My system has a 50% improvement with Sli activated in the control panel, while others are saying no improvement.

Single mission "London Attack" Sli de-activated 30--48fps.
Same mission Sli activated 35--80fps.

The high fps are present at the start and deteriorate as the action gets aggressive with flack and fighter action (which I would expect as normal) then increases again as the action drops off.

I am running a low end Sli system (as can be seen from my sig) but have a playable sim, over water I am getting fps 90--120fps Sli activated.

Maybe if the stutters that are occuring that a lot of us are getting are fixed then we might see some more improvement.

[jcenzano]

keep on dreaming...

I have been asking politely for an answer abot SLI and all I got was SILENCE.

hpo you have better luck. Anyway my COD is shelved until I get propper SLI support.

[6BL Bird-Dog]

From experiance I got various results with different card combo`s single and X-Fire.
1x AMD Saphire Toxic 5870 Oc, poor frame rates and micro studders,had to use medium settings .
2x AMD Saphire Toxic 5870 Oc,best ever performance when the early patch release enabled X-Fire,Max settings, good high frame rates and only the microstudders lower altitudes.Ruined when a small patch was bought out within hours because of graphics anomolys with Nvidia systems.
1xXFX HD 7970 Black Edition,Improvement on single 5870, but running at Very High in game settings made little difference compared to 2x AMD Saphire Toxic 5870 Oc,frame rates improved slightly.
2xXFX HD 7970 Black Edition,with both last Alpa and Beta patches more or less the same as a single XFX HD 7970 Black Edition performance slightly improved at highest settings.
I tested the same cards and setups on the rig in my sig and did compare performance with RoF and iL2 1946 ,the latter of which does not have X-Fire support.
In Rise of Flight as I Improved my Gpu hardware I was able to increases my quality settings with also an increase in FPS .The 2x AMD Saphire Toxic 5870 Oc performance was slghtly slower than a single XFX HD 7970 Black Edition.
2xXFX HD 7970 Black Edition runs fluidly with all settings at max with the exception of AntAliasing which Inever run above 2x as it murders the fps in ROF.
iL2 1946 ran maxed out on all combinations ,seamlessly on 2xXFX HD 7970 Black Edition, with the Average 60 FPS limited to 60mhz(my native screen res),but max frames are almost always over 1000fps.
The Clod dev team hit the sweet spot once for me on X-fire but have never unfortunately got close since ,well at least for AMD GPU`s.
In Cliffs of Dover`s present state apart from increasing in game video quality settings performance wise X-Fire is not functioning in anyway near to the Early X-Fire patch release which on my system was awesome compared to any patches before or after,the textures looked much better then too if a little bit too bright.
__________________

[nonoptimalrobot]

CrossFire and SLI have been designed to "just work" behind the scenes without any effort by the developer of the application. However, there are a lot of driver side decisions that need to be made about how work should get split between the GPUs that the actual application is better suited to make. ATI and Nvidia have provided ways for developers to do just that but they rarely do. On top of that there is a minefield of scenerios that arise when data is being exchanged between the CPU and GPU that can cause performance issues. Additional problems arise when gpu generated data from the previous frame is used by the gpu on the next frame. These types of dependencies create massive stalls that single GPUs setups never encounter.

ATI and Nvidia both provide detailed information to developers about how to best exploit multi-gpu setups; this information is available publicly but you need to be a graphics programmer to understand it.

The bottom line is that multi-gpu setups are horrendously under untilized unless the developer has taken the time to code a custom rendering path for both CrossFire and SLI configurations. As far as I know no developer has ever done this. Doing so is difficult and requires a great deal of forethought, something that was clearly not done during the development of COD's rendering system.

[Stublerone]

Again a sli thread? Hmmm, everything has ben said in other posts.

Thanks nonoptimalrobot for giving such information. Perhaps the sli users know, why it is still not working and will never work sufficiently in my opinion. There are simply too much hurdles and simply no good reason to do it.

Multi gpu can only behave good, if all buses, pipelines and all communication between all the components improve massively. You need a revolution in tech design to provide a sufficient way to use multi gpu.

Today, it is simply not possible and everyone, who bought sli should be aware of the fact, that this will never run. In some games, it shows some performance increase but others do not! Sli=crap, the general idea behind it=good, but with current hardware configurations not working!

I do not understand anybody, who tells his friends to buy an additional card to upgrade the system. It is simply not a good advice. And 2 x gtx 590 = even more problems. And do not talk about 2 x 3 gb = 6 gb -> this is not true. It is 2 x 3gb = 3 gb .... Technically not exactly correct as far as i know, but similar to that.

[6BL Bird-Dog]

To obtain the level of performance the first X-Fire patch gave there must have been some serious work done in that area.
I thought that other than the micro studders at low alt that single card users also had the Devs had actualy cracked the game performance issues.
The quck fix bought out within a few hours for Nvidia anomolies killed X-fire all round .

[tintifaxl]

Originally Posted by Stublerone

I do not understand anybody, who tells his friends to buy an additional card to upgrade the system. It is simply not a good advice. And 2 x gtx 590 = even more problems. And do not talk about 2 x 3 gb = 6 gb -> this is not true. It is 2 x 3gb = 3 gb .... Technically not exactly correct as far as i know, but similar to that.

Worse: it is 4 x 1.5 gb as each GPU needs its own VRAM.