Is SLI worth it? Benchmarks for 2-way & 3-way SLI

Hey Folks,

Eighteen months ago I bought an Aventum 3 system. My desire was to have a gaming computer that accomplished these goals:

     • Play games at the highest quality preset in each game
     • Play on a 34" ultra-wide monitor at it's native resolution (3440 x 1440)
     • Maintain 70 - 100 frames per second

I knew this wasn't possible with a single graphics card. A single card simply can't render that many pixels at the highest quality, and maintain an awesome framerate. So I went for overkill, and built a system with three GTX 980 Ti cards.

Here is what I discovered: Two-way SLI is wonderful, and it significantly helps in most games that I play. However, 3-way SLI is a complete waste. It barely helps in most games, hurts performance in some games, and introduces rendering glitches and stutters.

This weekend I decided to run some benchmarks to compare the performance of single-card, 2-way SLI, and 3-way SLI configurations. Here are the results:

Rise of the Tomb Raider
Settings: 3440 x 1440, Very High Quality, "Pure Hair" turned off
Testing method: Built-in benchmark
Single card: 71
2-way SLI: 99
3-way SLI: 84 (rendering glitches, and occasional stutters)
Summary: Use 2-way SLI for 39% better performance.

The Division
Settings: 3440 x 1440, Ultra Quality
Testing method: Built-in benchmark
Single card: 56
2-way SLI: 73
3-way SLI: 47 (with occasional stutters)
Summary: Use 2-way SLI for 30% better performance.

Thief
Settings: 3440 x 1440, Very High Quality
Testing method: Built-in benchmark
Single card: 73
2-way SLI: 115
3-way SLI: 117
Summary: Use 2-way SLI for 58% better performance.

Just Cause
Settings: 3440 x 1440, Highest Quality
Testing method: Watched framerate while playing
Single card: 75 - 80
2-way SLI: 75 - 80
3-way SLI: 75 - 80
Summary: SLI makes no difference in this game.

So, should you consider getting a 2-way SLI system? My recommendation is to start with a single high-end video card, the fastest that you can afford. If it's not fast enough for your needs, then add a 2nd card for SLI. However, don't get a 3rd card. You'll hardly gain any performance, and it may hurt the performance and quality in some games. For me, 2-way SLI is the sweet spot.

Tidbit #1: Some games don't support SLI when they are first released, but add it later. This was the case with Rise of the Tomb Raider, and The Division.

Tidbit #2: Do you have a 3-way SLI system already? How do you easily disable the 3rd card for performance testing? Just go to the NVIDIA settings, leave SLI enabled, but dedicate the 3rd card to Physx. This will force your system into 2-way SLI mode, and the 3rd card will be used for physics acceleration only. You can leave the 3-way SLI bridge in place.

Let me know if you'd like me to run benchmarks on additional games.

Edited by JamesAstro - 09 Jul 2017 at 12:35pm

Thanks for the practical information. I have read somewhere that sli support would be limited to two gpus in the future but things change all the time so...