To SLI or not SLI, that is the real GPU question

Insomnia 58
Insomnia 58

When looking at a GPU for enjoying games as they were intended, there's the decision as to whether or not to go with multiple affordable GPUs or a more expensive single unit. Having NVIDIA cards or AMD cards in SLI and Crossfire configurations can provide increased amounts of power for the buck compared against a single unit solution, but is it actually worth it?

How SLI and Crossfire work by connecting two compatible GPU cards with a bridge on a supported motherboard. SLI is slightly more restrictive — you need to install a pair of the same GPU, but they can be from different manufacturers. For example, you could hook up two GTX 980 Ti cards. As for Crossfire, you can mix up cards part of the same family. For more details on both systems, it's you should check out their corresponding support pages:

Configuring Crossfire and SLI setups can be carried out using either AMD or NVIDIA's control panel. Everything should be configured automatically once SLI or Crossfire is enabled. When firing up a game that supports multiple GPU cards, you should be able to enjoy increased performance compared to having just a single card installed. This is what the two systems are meant to push forward, but unfortunately there are some potential issues.

The Good

Install two GTX 1070s or GTX 1080s and you're packing quite the punch, so long as drivers support the game you wish to play (though increased performance can range from just 10% upwards). If scaling is solid you'll be able to bump settings to maximum and slide your resolution meter up to 4K with some comfortable frame rates.

DirectX 12 is set to change everything with SLI and Crossfire, allowing PC builders to combine more GPUs with increased support implemented by developers. We'd bet that we'll be seeing more support implemented for multiple video cards in the future, especially as more displays move into UHD territory.

The Bad

Insomnia 58

Insomnia PC

A major hurdle with multiple video cards is the support of games themselves. Unfortunately, even though you have multiple GPUs installed, configured correctly and meet all requirements, you may not be able to take full advantage of the extra capacity, depending on support for the title you wish to play. Even in 2016, this is still a problem.

GPUs draw power and produce some serious amounts of heat while under load. This can cause problems with heat management inside the chassis, but throw another card into the mix and you're doubling the output of warm air. Should you have a lack of cooling with a single card installed, you may need to look at improving flow with more fans or possibly invest in a water cooling solution.

Much like heat, more power is required for multiple cards. We generally recommend a 500W power supply for a single GPU-powered system. Having two cards installed will require more electricity and thus you'd probably want to bump your power supply up to at least a 750W unit from a reputable brand. Lastly, you may encounter an issue with stuttering and frame pacing, which could actually provide a less than consistent experience. Not what you'd expect from multiple cards.


I'd always go for a single more powerful card than forking out for two less powerful solutions. I understand that not everyone is lucky enough to be in the position to purchase a GTX 1080, but having an immense amount of power in a single unit is better for game support, heat management, and lower power costs. That said, if you wish for your computer to look even more bad ass than it already is, throwing another of the best graphics card options into the chassis is a great upgrade.

At the end of the day, buying a more powerful GPU means you can always get another and upgrade to SLI and Crossfire at a later stage. But what are your thoughts on multiple GPUs? Sound off in the comments if you're rocking two cards!

Rich Edmonds
Senior Editor, PC Build

Rich Edmonds was formerly a Senior Editor of PC hardware at Windows Central, covering everything related to PC components and NAS. He's been involved in technology for more than a decade and knows a thing or two about the magic inside a PC chassis. You can follow him on Twitter at @RichEdmonds.

  • Not
  • I prefer single card as well.
  • While a single card might be the most universally compatible solution (or economical from a new buyer perspective), I would strongly recommend that new buyers consider SLI / Crossfire motherboards when purchasing a new gaming computer. This article misrepresents average performance gains and compatibility issues. It's true that single cards are more widely supported, but among triple-A games there is very, very good support for SLI and Crossfire. In terms of performance for those titles you are talking about the difference between best settings at 30-60fps for a year or so (with 1 current gen card) or many years to come (with 2 current gen cards). By getting an SLI/Crossfire capable motherboard with 1 card, you give yourself the option to cheaply give yourself a very big performance upgrade down the line. A top of the line 1080 today costs ~$750. If two years from now you want to see significant gains for games made in 2019, you will have to shell out another $750 for a new card. Meanwhile, the guy who had the SLI capable motherboard can pick up a "dated" 1080 for probably $200 and see the same performance increase.
  • To the two that replied above me; Can you tell me why? Please.
  • I'm coming from a bad experience with SLI in my gaming laptop. Not all games were supported, and recording some games didn't work well with SLI either. Add to that heat and noisier fans. I had to switch between SLI and non SLI modes which required restart.
  • Dunno about those two, but personally, take whatever money you'd put towards a graphics card (SLI or not) and purchase the most powerful one you can. If its only enough money for one card, so be it. Duplicate that card whenever you have enough money to do so in the future. As it stands, a more powerful graphics card works for *every* game. SLI/Crossfire works only on supported games. Unless you're building to a specific game(s), there's no point with starting off with two lower powered cards as opposed to one more powerful card. If you can simply afford two of the most powerful cards and the cooling for them, then by all means, go ahead and do that. But if it comes down between one powerful card or two less powerful cards, I'd always go for the one powerful card.
  • That makes perfect sense. I just don't have much experience with that part of computers and am looking to build my own soon. Thanks to all who responded!
  • Complications.  Not all games support SLI.  Even if they do support SLI, it will in all likelihood only work in full screen view.  Not borderless windowed, not full screen windowed - only full screen view, which means no playing a game on one monitor while browsing the internet for a quest walkthrough on another monitor, no Netflixing and gaming.
  • Not sli, buy a console
  • Why would anyone want to downgrade?
  • So they can play more than only the first two Halo games on PC like me.  :-(
  • Having dealt with crossfire and SLI, I would agree with the other posters-stick with one powerful card. Power issues and waiting for driver updates to support games is a pain. I will say though, it is fun to tinker with if that's what you like to do.
  • You bring up a good point. I guess one scenario where i would suggest two less powerful cards verses one more powerful card is the scenario you stated about if you simply like tinkering. If that's your thing and actual performance is secondary to the tinkering/learning/etc experience, then yeah, two cards would be the way to go.
  • Having two dual slot cards doesn't leave much room to breathe, and if you have another pci card for something else, it's almost impossible to fit two gpu cards in
  • I fail to see the benefits over the cost of SLI.  A single GTX 1080​ is more than enough for all your gaming needs.
  • I think the concept is that with a one time investment, SLI keeps your rig more powerful for longer, assuming you stick with supported games. Plus, if you buy one single top of the line card now, when that's no longer as powerful as you need, it's cheaper to buy the same card again and add to your rig as opposed to buying the more expensive current video card. But in all honesty, it only makes sense if you can afford SLI with the two most powerful cards from the get-go and tinkering. 'Cause no matter what, you're going to need to tinker to get it to work right all the time.
  • While I perfer a single card, My computer is almost 5 years old and still doing pretty well with dual amd 7950's  I bought one when I first built the PC and then a second a year or so later on when they were cheaper. Overall I'd say it was probably worth buying a second card to keep the performance of my system up but I wouldn't flat out buy two cards.  
  • Stuttering a thing in this day and age? I haven't seen tearing in a while
  • I'm with the single card crowd, the main situations where dual cards make sense are when doing GPU computing. GPUs can do some high processor related tasks much faster and more efficiently than a CPU things like video encoding can go much faster if you let your GPU do it. of course having drivers that support it and software than can take advantage of GPU computing (stuff like mathlab/simulink and other items that used to run on clusters of servers can run off multiple computer's GPUs) is usually the issue.
  • There are other applications for multiple graphics cards such as folding, mining, etc. For gaming I never thought of lesser cards. The other factor is multi monitor or surround gaming. That is higher than 4k. True sometimes the game doesn't work with SLI or Crossfire, but what other solution can power 3 x 4k monitors. SLI is an enthusiast endeavor.
  • Can a single 1080 run 3 monitors? I have 2 460's to run them now. Would like to upgrade but not positive a single will work.
  • I have three 1920x1200 monitors running ultra settings with a single 1070, i7-3770K, 16GB RAM.
  • I'm sure it can. My surface pro 3 powers it's own 2K (qHD), a 24" 1080p monitor and a 28" 4k all at once for total resolution of like 10k x 7k and that's on Intels integrated yes, I'm quite positive a 1080 card could do better.
  • It wasn't a matter of horsepower. When I built this tower a single 460 didn't have the outputs for 3 screens. SLI was the only way at the time. I think AMD had capable card but the second 460 was a better deal.
  • I have an iRacing simulator running on two GT 460 in sli because a single card could not run three monitors. I understand now a 1070 or 1080 single can. Anybody know for sure? Gen 1 i7 is 4-5 years old, time for an upgrade and a single 1080 would be WAY cheaper if it works. Plus I can get a 6800K, Broadwell-E if I only need a single card.
  • I would be all for it if two $200 cards performed better than one $400 card.
  • I would prefer a (much) more powerful GPU than my current GTX-550Ti, but that's not a possibility for me money-wise. GTX 9XX or 10XX are complete pipedreams for me, and even 7XX and the majority of 6XX is out of the question. So, with that limitation, comparing single cards on Futuremark's GPU listing gives an idea what comes in the region of roughly double a 550Ti and comparing that price tag, even 2nd hand to a 2nd hand 550Ti to put in a SLI setup makes the choice rather simple.
  • Just don't do it
  • I agree with the author, always go single more powerful card if possible. Dual card solutions are expensive, require developer support to get gains from, are poor in terms of efficiency (200% the gpu power for 50-80% increase in performance), generate excessive heat, and require lots of power.
  • Also you have too keep in mind if your CPU and motherboard have the pci-e lanes available to run both cards. Mostly only the higher end x99 chipset can't use the full potential of sli or crossfire.
  • I currently have an SLI rig and I love it...sometimes. SLI is fantastic when it works and when developers actually program to support it. The issue is that there actually a move away from multi GPU gaming, not to it as suggested in this article. More and more games are released without an SLI profile and most of them never end up getting the support added. There are ways to force it sometimes but that's not how it should be. Cards are getting more capable so developers are getting lazier, (Just look at how bad games have been at the time of release). The combination means less multi GPU support. DX12 is non existent and irrelevant at this point as there are less than 50 games that even support it and regardless of what support it brings, the new cards max out at dual card setups. No more 3-way or 4-way SLI. The single card solution would be great if the cards were more capable. As it stands, even the 1080 struggles if you want to game at 4k with 60+ FPS. Same with VR, the technology for higher resolution VR exists but the current cards aren't capable of pushing it. Which is why it would be nice for them to figure out how to properly implement SLI in VR. I actually think all games should be required to support multi GPU setups from the start. Companies advertise SLI machines to get people to splurge on them. Customers end up spending an extra grand on these machines and then find out that 70% of the time they can't use it and that percentage is only increasing with the newest releases.
  • NVIDIA has a nice system for using SLI in VR setups as part of their "VrWorks" toolset. Like all effective performance tuning, it requires a good amount of effort on the developer's part to use it fully, and it becomes a separate code path from a regular non-SLI stereo render, so testing time also doubles. Developers  not implementing SLI (both in VR and traditional games) at launch is not a matter of laziness, it's a matter of not having enough time to do it properly, versus the small market that has SLI machines.  It's just an unfortunate fact of modern development. The market would have to significantly change (no holiday rush for sales, no sales fall-off one month after release, longer development times, games would be even more expensive) to allow for the type of full software engineering required to have every game be "perfect" at launch. No one feels this pain more than the developers who worked on the game.
  • 2 1080s is cheaper than 1 titan xp and i wouldnt recommend a titan xp to anyone with 1500 usd to burn. Then again the 1080 ti will probably be out in january.
  • I've never run either a SLI or Crossfire setup, but after hearing the praises of these technologies for literally more than a decade, it is mind boggling to me that there is still such a lack of support for it in games. You would think game programmers would code their software with this in mind regardless of whether it's a AAA title or not, but maybe that's just me being over-optimistic.
  • Won't DirectX12 fixes all the problems of Sli / Crossfire in the near future when more DirectX12 games will be more available or the developer's will still have to add game support for
  • One point FOR SLI... I had the fan die on one of my cards. It was still under warranty, so I sent it to Gigabyte to be repaired. I wasn't without my computer for that period of time. It wasn't as powerful, but I could still play some games.
  • If you do 3D content creation, SLI may be a great option for some of the new GPU renderers.
  • Currently have 980 SLI so I won't be upgrading anytime soon. But out of curiousity, which would you guys choose? Titan XP or 1080 SLI? Main use is VR and 4K gaming eventually. My current setup balks at driving 2 monitors and my 4K TV though.
  • Crossfire all the way. Been doing it for years and while yes you can have compatibility issues for the most part the gains out way the issues.