Wierd SLI Issue (video included)

[sephis 10]

Hi,

For some reason I've come across a weird problem in ARMA 3. When I have SLI disabled I get 99% GPU usage and, with SLI enabled, the cards run at 45-50% usage each BUT when I have SLI enabled and I look at the floor, both cards go to 99% usage. Can anyone think of why that might be? I also get 99% usage on both cards on the main menu with the island rendered in the background. I originally thought SLI wasn't working because it isn't yet supported but it looks like it is ...just not working properly.

I've posted a video to show I'm not making it up...

http://www.youtube.com/watch?v=vrl_YqlQQKo&feature=youtu.be

Any help would be much appreciated.

My PC specs are

i5 4670 @ 4.4ghz

8GB DDR 1600Mhz

2x GTX680's

250GB Samsung SSD

Edited September 18, 2013 by sephis

[ramius86 13]

lol that's funny, I will try this later...

Do you have also the mirrors glitch in vehicles?

[sephis 10]

lol that's funny, I will try this later...

Do you have also the mirrors glitch in vehicles?

You mean the flickering? If so yeah I do get that also unfortunately.

[ramius86 13]

Have you tried force one gpu in nvidia control panel? Now I use only one 680 and all is ok and also my fps are almost the same... gpu 99% = > 40+40 % sli

[sephis 10]

Have you tried force one gpu in nvidia control panel? Now I use only one 680 and all is ok and also my fps are almost the same... gpu 99% = > 40+40 % sli

Yeah this is what happened with...

Forced Single GPU

http://imageshack.us/a/img713/3127/9cgv.png (2437 kB)

SLI Enabled

http://imageshack.us/a/img827/5184/zwqz.png (2481 kB)

[ramius86 13]

ahhaha yes, almost the same result hahah! Have you tried change compatibility bit sli in nvidia inspector ? I think it's the only solution for, maybe, let this sli work... untill some driver will fix this I hope..

You better go with one single GPU for rendering and let the other for the physx.. In this way, incredible but true, you have more fps than the sli :P

Let's wait and hope...

[sephis 10]

ahhaha yes, almost the same result hahah! Have you tried change compatibility bit sli in nvidia inspector ? I think it's the only solution for, maybe, let this sli work... untill some driver will fix this I hope..

You better go with one single GPU for rendering and let the other for the physx.. In this way, incredible but true, you have more fps than the sli :P

Let's wait and hope...

I've tried change using the second card for physx but again, there is no change to performance whatsoever :-( Change compatibility bits to what?

Have you tried out the new drivers yet? I'm away for a few days so have to wait until Monday to try them out.

[ramius86 13]

Don't thing something is changed, I will try this evening but nothing in driver's changelog about ArmA 3 sli profile... I will try to change bit compatibility random with some games and see if something change but no expectancy about that , just a try...

[rundll.exe 12]

Nothing is broken here... It's just that other hardware than your video card is limiting the FPS (CPU/RAM or bus speed, but let's assume CPU here)

When you look at the ground, for some reason your FPS is limited by your GPU (max usage), but when you look at objects, your CPU bottlenecks the FPS, and your GPUs are not used 100%, since there is simply not more work for them to do while it's waiting for the CPU to finish. If you disable SLI, it will be at 100 percent because it is the bottleneck most of the time.

The fact that the load shifts that much while looking at objects is another point of discussion though, and I can't really explain that.

[ramius86 13]

3930k@4,5 ghz, also tried with 5ghz

32gb@2400

gtx 680 SC sli with custom bios for fan ( also tried reflash reference )

ocz revodrive 3x2

arma3 is whole in ramdisk

If my cpu blttlenecks the fps... well I think Ill gona have to buy some double xeon configuration :bounce3:

( http://www.cpubenchmark.net/high_end_cpus.html it's 12° at 3,2 ghz ... )

Edited September 20, 2013 by ramius86

[sephis 10]

God I'm so f*cking fed up with people blaming CPU botlenecks. With every single hardware config, when people can't figure out what the problem is, just blame it on a cpu bottelneck. There is nothing wrong with my set up and SLI works great in every other game that uses it. There has to be something else causing the issue. It would be nice if someone from Bohemia commented. What's the point of having a suppport forum if they're not going to respond to issues.

[xXxatrush1987 10]

3930k@4,5 ghz, also tried with 5ghz

32gb@2400

gtx 680 SC sli with custom bios for fan ( also tried reflash reference )

ocz revodrive 3x2

arma3 is whole in ramdisk

If my cpu blttlenecks the fps... well I think Ill gona have to buy some double xeon configuration :bounce3:

( http://www.cpubenchmark.net/high_end_cpus.html it's 12° at 3,2 ghz ... )

mostly in such configurations ram is the limiting part:

even it says it has 2400mibs(or pseudo mhz), with high tRFC latency(over 200) it cant even match ddr3 1600(as tRFC is there mostly around 100)

in this case the ramdrive just slows you down.

also the gtx680 is at high desinty enviroments hard capped by its 256bit interface and its 2gb of ram, but even with 4gb of ram the small(for a high end videocard) memory interface don´t allow any further scaling. a single titan/gtx780/7970+ good ram(2133mibs) could get higher fps with an 2500k@4.5ghz than your system, unless you play only short viewranges, where the high arythmetic power of the gtx680 can perform as it should and streaming is less of a problem.

@sephis: could be good possible that the double pcie 8x interface of sli configurations on z87 board is capping the second gtx. in the end i would at least wait for an official sli profile from nvida.

[rundll.exe 12]

God I'm so f*cking fed up with people blaming CPU botlenecks. With every single hardware config, when people can't figure out what the problem is, just blame it on a cpu bottelneck.

(CPU/RAM or bus speed, but let's assume CPU here)

Doesn't really matter what the bottleneck is, but ArmA is not your average game, where the rendering is the most heavy part. If the simulation cycle (one frame, CPU/RAM/data) is not finished before the GPU is ready rendering, the load will not be 100% for your GPU, since there is no more work to do. Nothing will change that, unless the whole rendering is decoupled from the simulation...

If my cpu blttlenecks the fps... well I think Ill gona have to buy some double xeon configuration :bounce3:

Doesn't really matter what CPU you get, something will always be the bottleneck, and other hardware will not run at 100% load then.

You get 70-100 fps, whats the problem?

Edited September 20, 2013 by rundll.exe

[ramius86 13]

Not agree, I've played so many games with this configuration ( and hundres and hundres with others ) and I always check gpu/cpu/ram usage and ArmA is one, with some other games, that can't really use the hw power..

cpu isn't my bottleneck... maybe will be the pcie 3.0 on my asus rampage iv extreme? doubt about it.. maybe ram at 2400 ? don't think.. revodrive? dont joke!

No, no bottleneck here, the software is my bottleneck.

Yes, I got sometimes 70 fps but I prefer the double because my hw can , we aren't talking about a 80-90% usage but 40%.... So I cannot say all ok here, sorry :)

[sephis 10]

Another point to add to this is that SLI works as it should only if you play on 4K resolution. I made a post in the Nvidia forum asking what the issue was and someone posted a screenshot of it working fine but he was playing in 4K. Changed my res to that and suddenly started getting 90%+ usage on both cards. The only problem of course being that the frame rate was now the same as 1080p with a single card :(