Intro

11.11.2017 Update: For the most up-to-date SLI benching results using Core i7-8700K at 4.6GHz, please see The GTX 1070 Ti SLI Performance Review vs. the GTX 1080 Ti – 35 Games Tested.



What’s better than a GTX 1080 Ti, the fastest video card in the world? Two of them in SLI! But is it worth the extra $700 for the second GTX 1080 Ti plus the cost of a HB bridge for added performance?

This follow up to BTR’s launch evaluation of the GTX 1080 Ti is going to test the same 25 modern PC games at 4 resolutions – 1920×1080, 2560×1440, 3440×1440, and 3840×2160 – to see how well SLI’d GTX 1080 Tis scale. We have tested SLI and CrossFire before with rather mixed results. We concluded from our last evaluation of the TITAN X vs. GTX 1070 SLI: “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 mGPU gamer to fall back to DX11. We also note that recent drivers may break multi-GPU scaling that once worked. Even a new game patch may affect multi-GPU game performance drastically.”

We were able to borrow a second GTX 1080 Ti and we ran the same benchmarks as in the GTX 1080 Ti launch evaluation last Thursday. We removed the backplate from the bottom GTX 1080 Ti so that the top card could intake air more easily and we used our EVGA HB SLI bridge.

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The EVGA HB SLI Bridge

No longer do the flexible ribbon SLI bridges bundled free with SLI motherboards carry enough bandwidth for Pascal SLI. Now High Bandwidth (HB) SLI bridges are necessary to support the bandwidth for high display resolutions. We received a HB SLI bridge from EVGA which enabled us to run these benchmarks.

Our HB bridge is “single spacing” and it also features a RGBW switcher to feature Green, Blue, White or (even) Red.

Here’s a closer look.

Here is the other side:

Here is GTX 1080 Ti SLI installed and lit up. Since we use the “zero spacing” configuration, we removed the bottom card’s backplate so the top card could intake air more easily. It made a few degrees improvement to the hot-running SLI’s GTX 1080s. Temperatures of both cards generally stayed in the mid-80s C and occasionally neared 90C. Better cooling would be helpful as it is very likely that at least one of the GTX 1080 Tis throttled pretty regularly in our very warm (Summer-like) test room.

Let’s check out the test configuration.