Due to the fact that most modern games rely heavily on GPUs in order to run properly, gamers must have a powerful graphics card in their system if they want to be able to run their favorite games on higher settings.
And, if you want to max out today’s top games at higher resolutions (1440P, 4K, and beyond), even more graphics processing power is required.
While the ideal solution to handle more demanding games at higher resolutions (and higher refresh rates) is always just to grab the best graphics card available (right now that’s a GTX 1080 Ti), there is the option for some (especially those with unlimited budgets) to utilize multiple graphics cards in the same setup in order to try and get even more performance out of their systems.
Both NVIDIA and AMD GPUs offer technology (SLI and CrossFire) that allows 2-4 of their graphics cards to work together in a single system to help deliver more GPU power. But, is running multiple GPUs in SLI or CrossFire configuration an option that is worth considering?
In this article, we’re going to break down how SLI and CrossFire work and how they’re different, as well as discuss what some of the pitfalls are that come with running multiple graphics cards.
SLI vs CrossFire: A Primer on How They Work and the Differences Between Them
Both SLI and CrossFire accomplish the same thing: they allow a system to split the load of processing graphics-related data between multiple graphics cards.
Theoretically, having multiple graphics cards split up the workload of processing frames means that your system can render frames more quickly, but as you’ll see further down in this post, multi-GPU configurations don’t offer a linear scaling of performance (although, in certain games, dual GPUs can produce a near doubling of performance in terms of average framerate).
But, before we get into some of the pitfalls of multi-GPU configurations, let’s discuss the differences between SLI and CrossFire.
First, SLI is NVIDIA’s multi-GPU solution whereas CrossFire is AMD’s multi-GPU solution. Again, both are similar technologies in that they both allow you to utilize multi-graphics cards in the same system.
Both technologies also operate in two different modes:
- Split frame rendering: Essentially, the GPUs split up the workload of processing each frame. So, one GPU will work on one “portion” of the frame and the other GPU will work on the remaining portion
- Alternate frame rendering: The GPUs split up the workload by working on alternate frames. GPU 1 will handle frames 1,3,5… and so on, and GPU 2 will handle frames 2,4,6…
However, there are a couple of main differences to be aware of:
- SLI requires you to use identical GPUs (so a GTX 1080 can only be SLI’d with another GTX 1080—although, the brand of the card doesn’t matter), whereas CrossFire will work with different GPUs of the same architecture (an RX 580 can be CrossFired with an RX 570, but not with an R9 390)
- SLI requires that the two cards be connected with a cable or SLI bridge. AMD cards used to require that the multiple cards be connected, but in updated versions, AMD GPUs in CrossFire configuration now just communicate via PCIe 3.0
- SLI configurations are generally more expensive than CrossFire configurations because NVIDIA requires motherboard manufacturers to pay to be “SLI” certified, whereas AMD doesn’t require any kind of certification and, as a result, there are lot more motherboards—including budget-friendly options—that support CrossFire.
The Pitfalls of Using Multiple Graphics Cards
While utilizing multiple graphics cards has been a great way to help users get more in-game performance out of their systems, in recent years, the performance advantage of running SLI or CrossFire systems has diminished slightly.
In the past, more game developers took the time to develop their games to be compatible with multi-GPU technology. Nowadays, though, fewer developers are working to optimize their games for SLI and CrossFire configurations.
Still, though, running dual GPUs can provide a nice increase, with many benchmarks showing ~50% higher improvements when adding a second card.
Questions do surround the future of dual-GPU setups, though. NVIDIA themselves have even pulled back on SLI support on a few of their latest generation cards. Only the GTX 1070 or higher can be SLId. The GTX 1060 can technically be set up in multi-GPU configurations, but it is not officially supported by NVIDIA (they have not included the SLI connection ports on 1060s).
Another downside of running SLI or CrossFire setups is the costs involved make them a tough buy for anyone that has any kind of restrictions on their budget.
While one could argue that since dual GTX 1070s cost only slightly more than a single GTX 1080 Ti and often outperform a single 1080 Ti in benchmarks, that they offer a similar (or better) price-to-performance. However, the reality is that dual GTX 1070s will require you to spend more money on your power supply, motherboard, and your case/cooling. This is because dual graphics cards will produce more power consumption and heat, and will also require an SLI certified motherboard (which are typically more expensive) as well.
So, you have to factor in those extra costs when determining the price-to-performance of running multiple cards.
So, When Do Multi-GPU Configurations Make Sense, Then?
The main reason why SLI and CrossFire exist it to help users get more performance in scenarios where even the most powerful single GPU setup won’t cut it.
So, nowadays, that means scenarios like trying to run games at max settings on a 1440P 144Hz (or higher) monitor with 144FPS. Or, trying to run games on a triple 4K monitor setup. Or, really any other extreme scenarios along those lines.
While graphics cards like the GTX 1080 Ti and GTX 1080 do perform well in 4K gaming and can handle most games on higher settings on a 1440P 144Hz monitor, the reality is that they still aren’t quite enough in some of those extreme use cases.
And, that, really, is where multi-GPU configurations come into play. No, they won’t give double (at least, across the board), or triple, or quadruple the performance boost over running the same card on its own. However, if you’re looking to build a gaming computer so that you can play games on as high of settings possible, with as high of a framerate as possible (especially on a 4K or 1440P 144Hz monitor), then you’re probably working with a very high budget anyways. And, in that case, you can probably also afford to drop the extra money on a second (or third, or fourth) graphics card in order to squeeze out as much performance for those scenarios as possible.
The other instance where it makes sense to utilize a multi-GPU setup is when you have an older generation graphics card and it would offer you better price-to-performance to add a second card, rather than upgrading the old card to a higher-end single GPU.
For instance, if you have a GTX 970 and you’re looking to get more in-game performance out of your system, you might be better off picking up a second GTX 970 for about $175 (used) on eBay and that should give you a decent performance boost in the games that utilize SLI properly. On the flip side of that, you’d have to pay at least $400 currently in order to replace the GTX 970 with only a GTX 1070—which isn’t that significant of an upgrade when you consider that the GTX 970 is still a fairly new GPU.
Ultimately, if you are looking to build an extreme gaming computer so that you can push games at max settings with as high of a framerate as possible on higher resolution monitors with faster refresh rates, then going with multi-GPUs is an option you’ll want to consider.
Are SLI or CrossFire Right for You?
In this post, we’ve outlined what SLI and CrossFire are, as well as broken down how they work, what scenarios they make the most sense in, and what the potential pitfalls are in running them.
For most users, SLI and CrossFire don’t make a ton of sense. If you’re gaming on a 1080P or standard 1440P monitor, running multiple graphics cards probably isn’t worth it. If, however, you’re trying to max games out on a 4K monitor or a 1440P 144Hz monitor, adding a second GPU might help you handle those more extreme scenarios.