Serious Sam VR mGPU NVIDIA GTX Pascal Follow Up

Serious Sam VR was the first commercial enthusiast gaming title to include multi-GPU support with AMD's RX 480 GPU. Now the folks at Croteam have added mGPU support for NVIDIA cards as well. We take a look at how well NVIDIA's VRSLI technology fares in this VR shooter title.

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Serious Sam VR Gameplay Summary

SSVR is in its infancy and is a Steam Early Release title. The game is far from finished and its gameplay does not even come close to covering what is exposed currently in the menu system. Last week, Croteam did announce that Co-Op play is coming soon.

Good news, everybody! Cooperative game mode is coming to Serious Sam VR: The Last Hope!

When we started this adventure together, we promised to listen to your feedback and requests. And out of many requests, this one stood out: bring coop to SSVR! We listened, implemented and tested, and today we can confirm that we have an internal build that's coming along nicely and the patch should be out soon, bringing coop to the game!

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SSVR is an extremely fast paced wave shooter that will take many of us back to the "good ole days" of first person shooters. You likely already know whether or not this is your kind of game. I bought mine and am happy with it now and hopefully what it will bring to the table later on. Co-Op is certainly icing on the cake but it will be interesting to see how it is executed in gameplay.

Serious Sam VR mGPU Performance Summary

I would like to start here by pointing out the absence of the GTX 1060 in our tests. While originally we had hoped that mGPU might be supported in VR, that is not the case. SLI has to be configured in the driver for mGPU to be used in VR. It seems unlikely that the GTX 1060 will be used for mGPU in VR in the future.

The NVIDIA TITAN X Pascal GPU is certainly a monster card for VR. I might be bold enough to say that it delivers the Premium VR Experience. wink On a serious note, what is most interesting is that neither the GTX 1080 VR SLI or GTX 1070 VR SLI configurations used here today exceeded the TITAN X' GPU Render Time.

Keep in mind though, as long as our GPU Render Time stays below approaching the 11.1ms threshold, our Vive does not go into Reprojection. With that in mind, our TITAN X, GTX 1080, GTX 1080 VR SLI, and GTX 1070 VR SLI experiences were all "the same" at our Ultra IQ settings. In SSVR at Ultra settings, the only card that "needed" mGPU / VR SLI is the GTX 1070. Also worth mentioning is that Serious Sam VR has an incredibly deep set of Image Quality controls beyond the presets we use here, giving you the ability to tweak out your settings for what gives you the best experience.

What I found most surprising was our mGPU / VR SLI scaling that we recorded. At first I thought our results were wrong because of what we saw when we ran mGPU / CrossFire with our AMD RX 480.

Using mGPU RX 480 in SSVR brought our average GPU Render Time down from 13.71ms to 8.755ms, far below our 11.1ms "cutoff" threshold. The visual quality difference is extremely noticeable and simply a much better VR experience as this bought SSVR gaming out of Reprojection, eliminating frame judder, and providing a much higher IQ level. Keep in mind that we are using "High/High/High" Performance IQ levels for our testing which I do consider GPU-intensive.

With the RX 480 at High SSVR settings we saw a drop in GPU Render Time by 4.955ms. That is huge compared to what we saw today with the NVIDIA cards. Our GTX 1070 mGPU at the same High setting in SSVR only dropped by 1.448ms. But that is looking at absolute values.

Looking at our Ultra settings we saw the GTX 1080 mGPU configuration drop our average GPU Render Time by 1.729ms, and our GTX 1070 mGPU drop it by 2.121ms. Certainly ~2ms does have the ability for you to change your IQ settings to give better image quality at the same gameplay experience. However, that does not come close to our 5ms drop we saw with our AMD RX 480.

If you look at percentages, our RX 480 mGPU configuration gave us a 36% lower GPU Render Time. If we look at the GTX 1070, it gave us an 18.6% decrease at High IQ and a 20.6% decrease at Ultra. We saw similar scaling with the GTX 1080 mGPU with a 19.7% decrease.

I have reached out to NVIDIA and Croteam about our results, although our readers are the first to see all the VR gameplay data in depth as it is shown and explained here. NVIDIA told me that they did not have data currently and Croteam has yet to respond. So hopefully we will followup on this soon.

The Bottom Line

Using NVIDIA GTX 1080 and GTX 1070 in mGPU / VR SLI we saw better performance in Serious Sam VR: The Last Hope. We however only saw a true benefit of using mGPU with our GTX 1070 cards. Our scaling with NVIDIA was simply not on par with what we saw when using our AMD RX 480 cards in mGPU / CrossFire in SSVR. This has left us with questions which we hope to get answered by NVIDIA and Croteam. Is NVIDIA harder to optimize for? Are we seeing hardware limitations? Right now we simply do not know. Nonetheless I still feel like the safest bet in terms of VR performance and VR value going forward remains on focusing on the best single GPU card and configuration that you can afford at the time of buying. I would not wager that mGPU is going extend your upgrade path a year from now by adding a second card.

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