Intro

The GTX 1070 Ti SLI vs. GTX 1080 Ti Review – 35 Games tested – We declare the performance winner!

What’s better than a GTX 1080 Ti, the fastest video card in the world beginning priced at $699? How about using two of the new GTX 1070 Tis in SLI for $900! But is it worth an extra $200 for the second GTX 1070 Ti plus the approximately $45 cost of a high bandwidth (HB) SLI bridge for added performance? Will GTX 1070 Ti SLI even beat a single GTX 1080 Ti in our 35-game benchmark suite?

This follow-up to last week’s launch evaluation of the GTX 1070 Ti is going to test the same 35 modern PC games at 3 resolutions – 1920×1080, 2560×1440, and 3840×2160 – to see how well SLI’d GTX 1070 Ti’s scale in comparison to a single GTX 1080 Ti. We have tested SLI and CrossFire before many times with rather mixed results. After finding that nearly half of our then 25-game benchmark suite had scaling issues with SLI just nine months ago, we concluded this from our last evaluation of GTX 1080 Ti SLI using Intel’s Skylake platform:

“GTX 1080 Ti SLI at $1400 is in a class completely by itself. But if you play the very latest games on Day 1 and rarely revisit your games, SLI may not be your best choice. Not every game will scale with SLI and many DX12 games do not scale at all.”

We purchased a second GTX 1070 Ti and we ran the same 35-game benchmarks as in the GTX 1080 Ti launch review last Thursday. Since our last SLI evaluation, we have upgraded to a Coffee Lake Core i7-8700K with all six cores locked to 4.6GHz by our ASRock Z370 Killer SLI/AC motherboard. This motherboard allows for a full space between the SLI’d cards, and temperatures were never an issue although the hottest card did get close to 84C where throttling begins. The aftermarket Gigabyte GTX 1070 Ti Gaming OC 8G card runs generally below 60C as the bottom card, and as a result the locked-on Boost core clock is usually 1923 MHz. The GTX 1070 Ti Founders Edition runs hotter as the top card because it is heated from below by the Gigabyte GTX 1070 Ti, and its locked-on Boost averaged slightly less at 1911 MHz.

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The HB SLI Bridge

No longer do the flexible ribbon SLI bridges bundled free with SLI motherboards carry enough bandwidth for upper-midrange Pascal SLI. High Bandwidth (HB) SLI bridges are necessary to support the bandwidth for high display resolutions. Here is a chart from NVIDIA’s GTX 1080 Reviewer’s Guide:

From our testing, we didn’t see any major performance differences between using a single ribbon SLI bridge and the HB SLI bridge for GTX 1070 Ti SLI. Rather we noticed an improvement in frametime delivery – smoothness is improved by the higher bandwidth provided by the HB bridge.

It is obvious from the games that chart frametimes that the HB SLI bridge provides a tangible smoothness improvement over using a ribbon bridge at 4K. Micro-stutter is more evident to us using a SLI ribbon bridge at 4K, and we believe that it can have a negative subconscious effect possibly producing irritation to a gamer even if it is not obvious while playing.

What about using 2 Standard Ribbon SLI Bridges?

From our own testing, we found no positive performance or frametime impact whatsoever by using two ribbon SLI bridges over one bridge contrary to popular opinion expressed on some tech forums. We asked NVIDIA about our research and they confirmed in no uncertain terms that using 2 standard bridges together are not recommended:

“With the ribbon cable system, each SLI connection runs independently regardless, so adding the second ribbon provides no benefit.”

We originally received a HB SLI bridge from EVGA, but it was designed for “zero spacing” between the cards so we had to purchase a 3-slot HB bridge which is manufactured by ASUS and we used it for all of our GTX 1070 Ti 4K SLI benching.

Let’s check out the test configuration.

Test Configuration

Test Configuration – Hardware

Intel Core i7-8700K (HyperThreading and Turbo boost is on to 4.6GHz for all cores; Coffee Lake DX11 CPU graphics).

ASRock Z370 Killer SLI/AC motherboard (Intel Z370 chipset, latest BIOS, PCIe 3.0/3.1 specification, CrossFire/SLI 8x+8x)

HyperX 16GB DDR4 (2x8GB, dual channel at 3333MHz)

GTX 1070 Ti 8GB , Founders Edition , stock clocks, supplied by NVIDIA

, , stock clocks, supplied by NVIDIA Gigabyte GTX 1070 Ti Gaming OC 8GB , stock clocks

, stock clocks GTX 1080 Ti Founders Edition 8GB, stock clocks, supplied by NVIDIA

stock clocks, supplied by NVIDIA ASUS HB SLI bridge

240GB HyperX SSD, supplied by Kingston

2TB Toshiba 7200 rpm HDD for storage

EVGA 1000G 1000W power supply unit

EVGA CLC 280mm CPU water cooler, supplied by EVGA

Onboard Realtek Audio

Genius SP-D150 speakers, supplied by Genius

Thermaltake Overseer RX-1, full tower case supplied by Thermaltake

ASUS 12X Blu-ray writer

Monoprice Crystal Pro 4K

Test Configuration – Software

–Nvidia’s GeForce 388.09 GTX 1070 Ti launch drivers were used for the GTX 1070 Ti’s and for the GTX 1080 Ti – except for benching Wolfenstein: The New Order with –GeForce 388.13. The only difference between 388.09 and 388.13 is optimized support for Wolfenstein and we benched GTX 1070 Ti SLI using the very latest drivers. High Quality, prefer maximum performance, single display.

–VSync is off in the control panel.

–AA enabled as noted in games; all in-game settings are specified with 16xAF always applied

–All results show average frame rates including minimum frame rates shown in italics on the chart next to the averages in smaller font.

–Highest quality sound (stereo) used in all games.

–Windows 10 64-bit Home edition. All DX11 titles were run under DX11 render paths, ten DX12 titles are run under the DX12 render path, and two Games use the Vulkan API (and 1 game also uses the OpenGL path)

–Latest DirectX

–All games are patched to their latest versions at time of publication.

–MSI’s Afterburner, latest version used for NVIDIA cards.

–OCAT, latest version

–Fraps, latest version

30 PC Game benchmark suite & 4 synthetic tests

Synthetic

Firestrike – Basic & Extreme

Time Spy DX12

VRMark Orange Room

VRMark Blue Room

DX11 Games

Crysis 3

Metro: Last Light Redux (2014)

Grand Theft Auto V

The Witcher 3

Fallout 4

Assassin’s Creed Syndicate

Just Cause 3

Rainbow Six Siege

DiRT Rally

Far Cry Primal

Call of Duty Infinite Warfare

Battlefield 1

Watch Dogs 2

Resident Evil 7

For Honor

Ghost Recon Wildlands

Mass Effect: Andromeda

Prey

DiRT 4

Project CARS 2

Middle Earth: Shadow of War

Assassin’s Creed Origins

Destiny 2

DX12 Games

Tom Clancy’s The Division

Ashes of the Singularity

Ashes of the Singularity: Escalation

Hitman

Rise of the Tomb Raider

Deus Ex Mankind Divided

Civilization VI

Gears of War 4

Sniper Elite 4

Total War: Warhammer II

Vulkan Games

DOOM

Wolfenstein: The New Order

Nvidia Control Panel settings:

We used MSI’s Afterburner to set the power and temp limits to their maximums.

We used MSI’s Afterburner to set the GeForce cards’ Power and Temperature targets to their maximum.

Calculating Percentages

There are two methods of calculating percentages. One is the “Percentage Difference” that we originally used to compare the GTX 1080 versus the TITAN X, and the other is “Percentage Change” which we are using now to show the performance increase of GTX 1080 Ti SLI over a single GTX 1070 Ti.

For the percentage change, we mean the increase in framerates between a GTX 1070 Ti and GTX 1070 Ti SLI divided by the absolute value of the original value in FPS, multiplied by 100.

Percentage change may be expressed by the algebraic formula: ( ΔV / |V1| ) * 100 = ((V2 – V1) / |V1|) * 100

Let’s head to our performance charts.