130FPS with 2xTitan Black on 4k - but just for 60sec

[Dropship Pilot]

Hi guys,

 

I'm looking for new hardware for DCS world. I currently have the opportunity to test DCS world 1.2.8 on a system with a stock 4770k, 16GB ram, and 2xTitan Black (6GB each) in SLI on a single 3960x2160TV limited to 30Hz by HDMI.

When I start the first A10C instant mission (Easy - East Georgia - Spring) I initially get 120-130fps and the green SLI status bar shows both GPUs at about 80%. (Looks and feels great!!! :thumbup:)

The problem is, that after a minute or two the fps goes down to 40-50fps and the SLI status bar goes down to about 30%. This effect is independent of the viewing direction and not reversable. E.g. I have to restart the mission to get back to 130fps.

When I disable SLI (e.g. running a single Titan Black) I get about 50-70fps throughout the mission with no strange effects.

 

I wonder if any SLI user here observed the same effect (and maybe has a solution).

 

Cheers,

DSP

[Exorcet]

I can't answer anything about SLI, but don't forget that DCS is to be receiving a new engine soon, with part of the goal being modernizing the software. It might not be beneficial to shop for hardware based on the current engine given that it's on the way out (as early as this year).

[eekz]

Make sure that your Titans do not lower frequencies due to high temperatures. Two of them working at 80% can produce really much heat I assume.

[Dropship Pilot]

Exorcet, thanks for the reminder, but sadly I don't have much choise if I want to do any flying in the next 6 month...

[Dropship Pilot]

eekz, I'll doublecheck the temperatures, but had no problems with the valley benchmark. Also wouldn't the GPU usage go up when the Titans start to clock down?

[skouras]

Great hardware buddy!!!

[Dropship Pilot]

Great hardware buddy!!!

 

Yep, but sadly it isn't mine......(yet :music_whistling:)

 

As for the temperatures - I paused the sim after the initial cockpit zoom while it was still at 130fps and waited a few minutes. When the cards had stable temperatures the fps had dropped to about 110fps. When I continued I had the same effect as before. Killed the first two trucks with the gun, turned toward the patrol and dropped to 50fps.

However, I noticed that contrary to what I said earlier the sim sometimes switches back to the 'high fps mode'. However, I couldn't find any connection to the temperatures or the clock speeds.

[AtaliaA1]

SLi in this Software has been beat to death. No one has had success with SLi sense I joined the Forum. I remember a lot of talk about it as the Software received a Graphics update, but unfortunately it didn't change anything.

 

This is a DirectX 9 Title, it wasn't optimized for SLi. Do a search in the Forum U will see all the post on the subject and no good results. I do remember one post a user stated He increased FPS but we thought it just a fluke or related to something else in his configuration.

 

As the Software starts up the calibration of the Fraps measuring engine is gearing up, that 120FPS isn't accurate it is just the software finding the mean in the equation.

Edited June 23, 2014 by AtaliaA1

[xxJohnxx]

Maybe also try to use the default DCS FPS counter. RCtrl+Pause is the key command I think.

[Dropship Pilot]

I've been using the ingame fps counter. When it drops from 130 to 50fps the external (NVIDIA) SLI bar also drops from 80% to about 30% GPU load.

So it's not just the fps counter that's acting up here.

 

Cheers,

DSP

[runny]

Maybe your personal nuclear powerplant isn't quite keeping up with your rig.

[atsmith6]

Hy Dropship Pilot

 

I run DCS on a 780 ti and get the same FPS behaviour you do. If I take the SU-25 out then at times I have in excess of 110 fps and at others under 60. When I deploy weapons and see the explosions the FPS can drop to the low 40's.

 

It's purely a function of how much is on screen. You can easily reproduce this:

1. Write down you current graphics settings

2. Set all settings to maximum (except maybe the trees)

3. Take off in the SU-25 and fly north along the coast

4. Enable the FPS display

5. Notice that when you're looking over the town with tons of buildings your FPS is likely far lower than when you look over the ocean.

6. Fire a bunch of rockets into the ground and make sure the explosions stay in your field of view - notice that while the explosion is happening you are likely to have a HUGE FPS drop.

 

Two things are happening here:

1. The more objects (like town buildings) the graphics card needs to draw, the bigger the hit

2. Any dynamic scenery like civilian traffic and other sim aircraft (and who knows what else) will also be taking a load on the CPU.

 

The first is easy to see using the method above. The second can be a pain because we don't know what the developers do in the CPU time. There is also IO (which is slow) that happens and you can see this when DCS decides to stutter. This is because ultimately there is one huge limitation that no graphics card can compensate for. Each frame, the CPU is used to do the actual simulation. When this is happening, the graphics card is doing nothing. It's essentially waiting for the CPU to tell it what geometry to draw and which transformations to apply. Only then does the graphics card do it's thing and it's only THAT time slice the card can affect.

 

That was a bit of a ramble and slight over-simplification but I hope that helps you understand the limitations in performance that you are seeing a little better. I am a games developer myself so I speak from some experience.

 

have a great day...

[Dropship Pilot]

Maybe your personal nuclear powerplant isn't quite keeping up with your rig.

 

LoL - a nice ARC reactor in the basement should be enough. :smilewink:

 

It can keep up with the Valley Benchmark (full load on both GPUs), so DCS shouldn't be a problem.

Edited June 23, 2014 by Dropship Pilot

[Dropship Pilot]

atsmith6,

I don't think the CPU is the bottleneck here as even when I climb straight into the sky the framerate isn't going up from 40-50fps. On the other hand there are instances where I can fly over large towns and forrests and still have 100+fps.

I'll check the smoke effects and CPU useage again. However, the fps drop usually happens when I'm well past the two (smoldering) trucks and before I even engage the patrol (and sometimes after the patrol is already out of sight again).

[atsmith6]

Ahh Ok. Well if you do figure it out I'd appreciate it if you'd PM me and let me know :)

[SkateZilla]

What SLI Mode are you using?

[Dropship Pilot]

I'm using the standard settings now. I've tested Alternate Frame Rendering 1 and 2 but the standard settings worked best.

IIrc, AFR1 and 2 gave pretty much the same results as no SLI at all.

[SkateZilla]

There's GeForce Experience Profiles, But I Run AMD, So I cant Really help.

https://forums.geforce.com/default/topic/548123/sli/dcs-world-sli-profile/

Edited June 23, 2014 by SkateZilla

[Mewle]

You say the screen is limited to 30hz?? If that is the case, slam vsync on and you have a steady 30 fps without tearing, as you said it doesn't drop below 40.

 

 

But yeah, I'm sure you'd be aiming for 60hz minimum if you were to acquire such a setup. I have been playing on an i7 4770k with a 3gb 780ti, DCS installed on a pretty savage ssd and with 16gb of fast memory and the fps does drop at points. But it usually picks up again once the viewed scene complexity drops. I can only imagine the SLI is not playing nicely.

 

Sli and x fire are, in my opinion, lame.

Why would you pay twice to get way less than double performance when you could spend almost the same money and get a better single card that is much closer to the golden 2xpower goal.

Edited June 23, 2014 by Mewle

[AtaliaA1]

Sli and x fire are, in my opinion, lame.

Why would you pay twice to get way less than double performance when you could spend almost the same money and get a better single card that is much closer to the golden 2xpower goal.

 

 

This is true for "Todays" Technology. That tech. was created in the late 90's, Unfortunately "Software" did not keep up and can little use the advantages of dual cards. especially a DirectX9 Title.

[*Rage*]

People often xfire/sli when the cards bought originally are much cheaper.

 

Case in point: I bought a top end 7970 for £360 initially 2 years ago. I can now xfire by buying an additional one for about £100 and have better performance than a 780ti in almost all games/benchmarks.

 

The reason I havent yet is because I want to see first what the graphical requirements are going to be for EDGE .

[rajdary]

Hi guys,

 

I'm looking for new hardware for DCS world. I currently have the opportunity to test DCS world 1.2.8 on a system with a stock 4770k, 16GB ram, and 2xTitan Black (6GB each) in SLI on a single 3960x2160TV limited to 30Hz by HDMI.

 

 

DSP

 

I think you ment that the screen is limited to 30Hz?? Because as far as i know HDMI is limited to 60HZ, maybe im wong?

[-Rudel-]

Honestly, you should be using display port for 4K.

[SkateZilla]

I think you ment that the screen is limited to 30Hz?? Because as far as i know HDMI is limited to 60HZ, maybe im wong?

 

HDMI 1.4 only offers 4K at 30Hz.

 

HDMI 2.0 will offer 4K at 60Hz

[rajdary]

HDMI 1.4 only offers 4K at 30Hz.

 

HDMI 2.0 will offer 4K at 60Hz

 

Ok, but then in a 780Ti running 3 monitors and all monitor recieving input through their HDMI with respective cable converted from the 780Ti, is that making the monitor give out 30Hz or 60Hz? I suppose its not 4K?