GTX 1080 Ti SLI Performance in 25 Games

Intro

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.

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.

hb-sli-1

Here is the other side:

hb-sli-2Here 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.

  • GhostMop

    Thank you for providing SLI results for the 1080 Ti and more importantly thank you for testing at 3440×1440. As someone who games at 3440×1440, I like to see that resolution tested so I don’t have to extrapolate from another resolution. I’m running 1080s in SLI and though the extra card is of dubious value, my gaming rig has a bit more flair with a pair!

  • nvooser

    These cards need 5k resolution to shine in SLI. Even at 4k, a single card can become CPU bound sometimes.

    • Mlambert890

      That’s not true. Maxing out settings in 4k no way do you end up CPU bound in anything. You can see that in any 1080Ti or Titan X Pascal review. There are a ton of games where they can’t even touch 60fps at 4k max.

      I moved from Titan X Pascal to 1080Ti SLI on a lowly 6700K with no overclock and saw a massive jump at 4k max in the games where SLI actually scales.

  • Tim Baker

    Here is footage captured from my computer which is running 2 GTX 1080 Ti in SLI mode. It is Tom Clancy’s Ghost Recon Wildlands captured in 4k UHD 2160p at 60FPS I just got it uploaded so it may not be processed into 2160p by youtube yet but here it is.

    Even with the killer rig i’m running the game is VERY demanding and it taxes even my system. None the less, I average between 80 to 100 FPS and have never dipped below 60. I think it could be optimized for SLI better.

    https://www.youtube.com/watch?v=_JnyxQY3kiI&lc

  • MattTS1

    I’m wondering how much thermal throttling is ruining the potential SLI performance here? Given the 0 spacing and 80s to 90s temperature I’m betting a lot.

  • Tim Baker

    I am wondering if I need to invest in a high bandwidth SLI bridge. I ran Unigine heaven 4.0 benchmark on my 1080 ti SLI setup and the results seem to leave something to be desired even though they are pretty awesome.
    Can you tell me what you think? You can see the video here.

    https://youtu.be/XQ8z360bGTM

    • apoppin

      A HB SLI bridge is a good idea as the older SLI ribbon bridges cannot provide enough bandwidth at 4K.
      http://www.babeltechreviews.com/titan-x-vs-gtx-1070-sli/

      • Tim Baker

        Thanks for the tip. That would explain the vast performance difference between 2k and 4k. One problem on my old system I have 2 1080 one overclock one reference I’ve been using the Asus flex SLI bridge which does use both spots. However the new hb bridge are rigid and thus need the pcbs to be the same depth. Does anyone make an extended maybe?

        I got the new hb bridges today but so far can only use it on my tis… I’ll be doing benchmark comparisons this week.

  • Quozzo

    Interestingly enough, the games that dont support SLI actually dont need it. The FPS on all resolutions almost max out, or are above, the screens refresh rate.

    • Mohamed Boukachabia

      at the current gen of monitors you dont really need fps above 60 at 4k but you should take a look at the monitors coming in 2017 4K HDR at 144hz , you really need the scaling otherwise nothing would be able to push the limits of these new monitors

  • 李琰

    I did a similar test. If you use a 6900K/6950X CPU and over lock it to 4.4GHz, you will find a big difference on 1080p with 2 GPUs.

  • Royale Martinez

    DAMN. Numerous DX12 games doing WORSE in SLI. That’s crazy.

  • Benjamin Johnson

    I run two reference 980’s (not Ti’s) and get very close to these numbers in 4k resolution. We’re talking maybe a 10fps difference. I’m running an older i7 4960x, and I bought the Nvidia HB 2 slot bridge, even though maxwell supposedly doesn’t utilise it. My cards are also zero spacing & run 80-82 degrees Celsius. Imo, not worth $1400 atm.

    • EnvymeRT

      Not to sound like a dick but here it comes …… if you think that a 980 even in SLI is only a 10fps difference you are talking out of your ass. 980s run roughly 50% slower than a 1080TI at 4k in ANY game….. you would need to run the 980’s in SLI to get FPS comparable to 1 card. Good job using the games that SLI does not scale as your benchmark for value.

      • Benjamin Johnson

        You are correct. It’s obvious 1080ti’s will blow 980’s out of the water. You cannot run any of these titles with only one 980. Maybe if you really dumb down the graphics, but then what’s the point, might as well stick to 1080p resolution. My point is, when I sli 980’s, I have more scalability in these titles than 1080ti in sli. This is evidence of that. My performance goes up, not parallel, or down. As of right now, you spend an additional $699 for bragging rights. That’s it. In the real world, cost vs performance is just plain stupid. Idk how many times you’ve spent hard earned cash on the lasted & greatest product, plug it in, and it’s performance wasn’t what you expected. There is “On paper” & “The Real World”. A lot of Hype. If developers find it profitable to spend the time to optimize SLI, then, duh…. I would jump on the bandwagon.

      • Crazycrab AJSA

        The older Maxwell architecture GPU’s obviously aren’t as powerful on their own but they scale much better in SLI than Pascal does, they even nativity support 3 and 4 way. Nvidea have been try to phase out SLI I think purely to entice people to buy a brand new card when they upgrade as opposed to connecting a second one. If you are going for a multi-GPU set up your better playing team red because Crossfire is used in the PS4 Pro (maybe the XBox Scorpio as well) so obviously they have to continue to support it. I’m not expecting the up and coming VEGA to match a 1080 Ti but I think it will scale much better in crossfire than the !080 Ti does in SLI.

      • Em Teezy

        1080 Ti overclocks like shit lol. 980 overclocks a lot better.

  • Lucas Kthulu

    I love you guys just for the fact that you include 3440×1440 benchmarks, keep it coming!

  • Jandré Terreblanche

    I understand it’s probably too time consuming for your test – but you should put forth a little more effort to find a multi-gpu profile that is better optimized for each game. You can see gains of over 80% on mankind divided if properly configured, not 29% as the default is (at 4K). This looks like test results from a multi-gpu setup by a person who has no clue what they’re doing.