A-10C exports + SLI problem

[GeneralDynamics]

I apologize if this has already been discussed elsewhere, but I wasn't able to find anything specific to this issue, and it's been driving me nuts for a couple years now. If anyone can help me out with this I may be able to avoid being committed to an institution:)

 

Please check out my profile for setup.

 

I know there's been a lot of discussion regarding use of SLI, both for and against, but again, I haven't seen anything that addresses the specific circumstances that I'm experiencing.

 

Now, the problem:

1. If I disable SLI and run on one GTX 780 with Helios/exports enabled on the touchscreen and fairly high settings and eye candy, I get around 60-90 fps depending, everything is buttery smooth.

 

2. If I enable SLI with the same settings and Helios/exports, my frame rate drops by half to around 28 - 30 fps, skippy, stuttery, bleah.

 

3. Now, if I turn off Helios/exports and run with SLI enabled using the 1 Screen monitor profile, spread across both the main screen and touch screen, I'm still rendering two screens, right? Well, my frame rate is 120 - 130 fps, smooth as silk! How can this be, if DCS does not take advantage of SLI??

 

EDIT: Just to compare apples to apples, I did the same as above with SLI turned off, and frame rate was around 80 fps.

 

4. The problem is not Helios, because with Helios turned off while still sending exports only to the touch screen with SLI on, the problem remains exactly the same.

 

Does anyone have any idea why on earth exports cause this problem with SLI enabled? I'm hoping the issue will go away with DCSW 2, but I'm not so sure as based on the above, it seems to be related more to exports sent to a second screen with SLI enabled, and not so much with SLI itself.

 

I've tried setting the SLI mode to alt frame rendering 2 and all the other suggestions, not much help. It's better if you consider flashing clouds and textures and microstutter better, and at best it only gets the frame rate back up to more or less that seen running with one card in non-SLI mode.

 

I'd welcome any thoughts on this folks could offer. Thanks!

Edited September 23, 2015 by GeneralDynamics

[Hollywood_315]

Interesting. I hit on a similar issue just now when setting up my new SLI rig. My first monitor is the main display, the second one is a touchscreen for HELIOS. Before SLI, all was well with the world. MFCD exports to the second display went fine, the main display showing the DCS main screen. However with SLI there seems to be a glitch: the driver crashes if the Center viewport is set to anything other than the full dual-display resolution in my case 3840x1080. Obviously I want to set it to 1920x1080 to confine it to my main display.

 

With some experimenting I can now get the export instruments now back on the second mon with SLI working and without any driver crashes, however this ONLY works if I have my main view spread out across the two monitors.

 

This is obviously not what I want!

 

It would be great if I can somehow hack my way into getting the SLI thing to work properly.

Investigations continue.

 

Maybe some expert can give their input on this.

[Hollywood_315]

Well, I got it to work by tweaking some of the NVIDIA driver settings

Not sure which one did the trick, but ok for now!

 

EDIT it's setting to AFR2 mode that fixes it.

Edited October 11, 2015 by Hollywood_315