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Unreal DK2 SLI - no effect

Hey there,

we have recently created an unreal 4 tech demo in order to test the performance with our SLI GTX 980 System.

Unfortunately the second GTX has absolutely no effect. Neither with the DK2 nor with a standard view through a monitor display. Is there something what we are missing? I have read a lot in different threads that you can achieve a performance boost through a SLI system , although there might be problem with the second GTX card in regards of the OR

However, it has absolutely no effect. When we try out other unreal tech demo which are available on the internet and forums we can clearly see the effect ( I'm only talking about non DK2 Demos - as an example the Apollo Tech demo) Also I think when starting a unreal 4 tech demo / application there should be a visible SLI Logo if activated through the Nvidia system option.

any advise is much appreciated.

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asked Mar 19 '15 at 09:38 PM in VR

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avatar image 1l2Hawk Mar 19 '15 at 10:00 PM

Have you gone thru most of the standard OR optimization tricks already before comparing the SLI performance vs a single gfx card?

For example, disabling Frame Rate Smoothing (Project Settings -> Engine -> General Settings -> Smooth Frame Rate = false). Or disabling TemporalAA (Global Post Process Settings -> Misc -> AA Method = FXAA or None). Or turning down the scalability settings from "Epic" to something lower. Or by killing any Aero effects on your Windows. Etc etc. There's a long checklist of things that will cap out the performance on a DK2, where maybe that 2nd card won't make much difference until your project is optimized properly.

avatar image kslay Mar 19 '15 at 11:26 PM

Maybe you misunderstood my post or I was not clear enough. It's not the case that the performance is very good right now. we have to decrease many many settings in order to achieve the 75 fps border for a decent OR experience. If that would be the case ( perfect performance ) than I would agree to your comment. please correct me if I'm wrong here. there is absolutely no difference in our fps when activating or deactivating the SLI system via nvidia settings - not one fps. exactly the same without the OR but of course with much better performance. However if used on a 4 K screen we achieve right now approx. 25-30 fps ( without OR)
even in that case the second GTX should give us more performance when activated. but there is no difference. I was wondering if you have to implement or activate the SLI feature inside the Editor?

is there any console command to check the graphic performance or SLI power just to be 100% sure that the second card is activated and in charge?

avatar image kslay Mar 19 '15 at 11:28 PM

just for your note , by just increasing the HMD SP value to 200 or even higher the second GTX card should come into play. But that's not the case...

avatar image PhanHat Jul 12 '16 at 08:11 AM

That still would be great to know: Does Unreal use SLI and how can I activate it?

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