Performance Summary Charts & Conclusion

Performance summary charts

Here are the summary charts of 35 games and 4 synthetic tests. The highest settings are always chosen; DX12 is picked above DX11 where available, and the settings are ultra or maxed.  Specific settings are listed on the performance charts.  The benches were run at 1920×1080, 2560×1440, and at 3840×2160.  All results, except for FireStrike, Time Spy, and VRMark show average framerates and higher is always better. Minimum framerates are shown next to the averages when they are available, but they are in italics and in a slightly smaller font.

The GTX 1070 Ti performance results are in the first green column and GTX 1070 Ti SLI results are shown in the second green column.  The 3rd green column shows GTX 1080 Ti performance results.  The first yellow column shows the percentage increase from the GTX 1070 Ti results to GTX 1070 Ti SLI results – negative scaling is shown as “negative”, while any number result is the GTX1070 Ti SLI performance increase over a single GTX 1070 Ti expressed as a percentage.  ‘Wins’ between the GTX 1080 and GTX 1070 Ti SLI are shown by Yellow font.

Out of the 35 games that we tested, 5 do not scale at all, 2 more games have mixed scaling results depending on resolution, and four other games need to be played in DX11 (or OpenGL) as they scale negatively in DX12 (and in Vulkan).  On top of this, Civilization VI has serious issues with uneven frametime delivery in SLI even with DX12 multi-GPU checked.  Yet these SLI results are far better than just nine months ago when about half of our 25-game benchmark suite of the time had serious SLI issues.

We also note that GTX 1070 Ti SLI is generally overkill for 1920×1080 as it generally scales rather poorly compared with scaling at higher resolutions although there are exceptions.  Ideally, a gamer would pick GTX 1070 Ti SLI for 2560×1440 to 4K resolution.  The games that benefit from SLI will sometimes have some dramatic performance increases, often from 20% to sometimes to well over 90% if the dev has worked to optimize it.  Total War: Warhammer II shows more than 100% scaling, but it is not an apples-to-apples comparison as we are comparing DX11 GTX 1070 Ti SLI to a single GTX 1070 Ti running on the DX12 API. 

Some DX12 games appear to have some real issues with SLI support and it has to be implemented by the developer for it to work at all.  However, we generally see a recent positive trend as some DX12 games implement SLI very well, and Gears of War 4 has even added SLI support months after release.

Let’s head for our conclusion.

Conclusion

This has been quite an enjoyable exploration for us in comparing a single GTX 1080 Ti against a GTX 1070 Ti, and versus GTX 1070 Ti SLI.  SLI scaling is good performance-wise in mostly older games and where the devs specifically support SLI in newer DX11 and in DX12 games.  When GTX 1070 Ti SLI scales well, it surpasses a single GTX 1080 Ti in performance; when it doesn’t, a single GTX 1070 Ti can usually manage 4K resolution with some visual compromises.

The $699 GTX 1080 Ti is certainly expensive but it stands alone as the world’s fastest gaming GPU.   However, SLI’d GTX 1070 Ti’s are out of reach of most gamers at over $900 plus about $45 for a SLI HB bridge.  It is pretty clear that CrossFire or SLI scaling in the newest games, especially with DX12, are going to depend on the developers’ support for each game requiring a SLI gamer to occasionally fall back to DX11.  We also note that recent drivers may break SLI scaling that once worked and even a new game patch may affect SLI game performance dramatically.

Compared with just 9 months ago, support for SLI has significantly improved and GTX 1070 Ti SLI appears to be a viable upgrade path for someone who buys one now.  We believe that a GTX 1080 Ti is better overall for ultra 4K gaming than GTX 1070 Ti SLI; and GTX 1080 Ti SLI may also become a future upgrade path.

The Verdict:

If you want an extremely fast video card configuration, GTX 1070 Ti SLI at $900 can easily beat a $700 GTX 1080 Ti when SLI scales.  But if you play the very latest games on Day 1 and rarely revisit your games, SLI is not your best choice.  And we would generally not recommend buying a pair of GTX 1070 Ti’s instead of a GTX 1080 Ti, although GTX 1070 Ti SLI is perhaps a viable future upgrade path for a GTX 1070 Ti owner who often revisits his game library.

Stay tuned, there is a lot more coming from us at BTR.  We just received an EVGA Z370 FTW motherboard from EVGA, and we are aiming for 5.0GHz or higher with our i7-8700K.  We’ll post the full review next week.  In the meantime, don’t forget to check out BTR’s growing tech community!  You can feel free to comment there or in the comments below.

Happy Gaming!

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5 COMMENTS

  1. Yeah SLI really *not* recommended, the reason being that when it doesn’t scale, it’s so bad that you basically don’t even want to play the game any more. You’re losing half your performance and generally speaking you can no longer run that game at 4k resolution. It sucks, and it happens a lot. If it happened more rarely it would be ok. However, maybe the developers and everyone just need to get a better handle of DX12. SLI could improve in the future. We are already seeing way better scaling. When BTR tested GTX 1070 SLI way back it wasn’t even close to the speed they just got with their Ti cards. Sure the Ti cards are faster, but not by that much. I’m wondering if the new CPU made a difference also.

    I’ve been running GTX 1070 SLI for about six months.

    • I think your idea is good and we are planning to compare Skylake vs. Coffee Lake, but the next step should probably be to benchmark GTX 1070 Ti SLI vs. RX Vega 64 CF using 50 games to update our old CFvSLI evaluation. It’s part of our ongoing plan for evaluating mGPU over many years. These kind of evaluations take a lot of time, so we have a brand new video card to review as soon after our EVGA Z370 FTW MB overclocking review is posted next week. We will return to SLI benching as soon as we can.

        • We’ll do our best to cover those topics. These kinds of evaluations each take a lot of time, so look for regular updates. Next up, is the EVGA Z370MB overclocking review before we return to video card benching.

          Thank-you all for your requests and suggestions!