In this guide, we take a look at SLI and which games make the best use of the technology developed by Nvidia.
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Why Is SLI Important?
SLI, otherwise known as Scalable Link Interface, is a proprietary graphics card scaling engine developed by Nvidia to allow multiple GPUs to be linked together within one machine. The multiple GPUs share the rendering of real-time graphics to create one single output.
The technology was initially developed way back in the late 1990s by 3dfx. Nvidia bought out 3dfx and thus become proprietor of the tech. The graphics giant reengineered SLI in 2004 to become the technology we currently see in most modern Nvidia GPUs.
SLI supports up to four GPUs at once (2-Way SLI, 3-Way SLI, 4-Way SLI), although for the consumer market the trend is to limit the use of the technology to two units.
The idea is to increase a machine’s rendering capacity by having multiple GPUs working in parallel, each undertakes an equal share of the workload, and thus improve the performance of games especially frames per minute count and shadows, lighting, and textures quality.
For SLI to work, multiple copies of the same GPU need to be installed in available PCI-Express slots and linked through the SLI Bridge connector, at which point each card works on independently assigned parts of the 3D rendering process before completed work is sent back to a ‘’master’’ GPU and forwarded as a unified output. The process is controlled by the graphics driver, which shares out the workload and decides rendering priority for each card.
Within the SLI framework, there are multiple rendering processes. These are Alternate Frame Rendering (AFR) and SLI Antialiasing (SLI AA).
AFR is geared towards better overall performance by having the GPUs use the added firepower to render as much as possible without any overlap. It assigns a specific number of frames to the two GPUs, and these work on them independently of one another. By way of example, frames 1-10 are covered by the first GPU, while the second GPU works of frames 11-20, and so on upwards.
SLI AA, on the other hand, is all about rendering the crispest, breathtaking visual experience with the hardware available, sometimes at the cost of performance by divvying up the antialiasing process. The GPUs are assigned antialiasing work on identical frames, but then the workload is divided when it comes to sub-pixel sampling, and each GPU covers a different set of points within the frame — the amalgamated result in a more visually enticing image.
Is SLI Still Relevant?
Since 2004, the SLI technology has come on leaps and bounds to keep up with the ever more demanding needs of modern games, particularly of the AAA variety. SLI tech still features in the majority of Nvidia’s line of GPUs, including the most recent RTX series, which boasts SLI transfer bandwidth upwards of fifty times that of previous technologies thanks to a new SLI Bridge coined the NVLink
Where SLIs relevancy starts to waver is when it comes to game developers. Optimizing a game for SLI support is a painstaking process and requires the release of purpose designed updates on the part of the developer and specific driver tweaks on the part of Nvidia.
More often than not, a AAA title records poor SLI performance at launch, that is until the patches and drivers mentioned above can be updated, and a stable SLI profile developed, at which point the technology unquestionably comes into its element and drastically improves games.
The first month is when SLI users suffer, but given time the experience becomes well worth it. For games that are a year or two old and support SLI, the performance is better across the board (20%-40% range generally), bar a few exceptions and variation in how much of improvement the tech makes.
For Nvidia, SLI as a proprietary tech is worth propping up and supporting for years to come; it means more GPUs are sold, increase their annual profits. With the advent of extremely powerful single GPUs (read GTX and the RTX line) more than capable of handling the demands of ‘’ultra’’ settings on the most power hungry games, the need for multiple GPUs is less and less apparent.
Developers are, therefore, increasingly less likely to invest time and resources into SLI support when the majority of players migrate or stick to the single GPU setup. The rendering techniques required off an engine to support SLI are complicated at best, and in many cases, bugs and fixes that affect a majority of gamers rank higher in a developers to-do list than SLI optimization. For these reasons, fervor for SLI support on the developer end is not as pronounced as it used to be.
SLI is also the GPU technology of the tinkerer by excellence. In most case, SLI profiles supplied by Nvidia and developers do relatively well, but more often than not, the in-game graphics options are there to be tinkered with before obtaining optimal performance.
Arguably, the golden age of SLI support was around the time when the Nvidia 900 series was all the rage around 2015-2016. The relative affordability of these GPUs made SLI a far more accessible technology.
In many ways, the GPU market is at a turning point where SLI could quietly be confined to the annals of history, or remain an albeit niche, yet in-demand technology.
By way of example, SLI is a good tech for those with the finances to build a state of the art dual RTX setup or those who are avid partakers in older games, say World of Warcraft, and can get their hands on two GTX 980s or GTX 970s.
Best Games That Support SLI
With the above in mind, a wealth of games support SLI and do so well, genuinely improving the visual quality of the game especially at higher resolutions, notably 4K.
Let’s take a look at the games with the best SLI profiles. You’ll note that many of them aren’t what you’d call ‘’new’’ games, which is symptomatic of the waning support for SLI. Recent heavy hitters such as Call of Duty: Black Ops 4 have SLI support and a dedicated profile, but the results are unsatisfactory with stutters, frame loss, and overall a much more jagged experience compared to using a single card.
The Witcher 3: Wild Hunt
CD Projekt Red’s enduring action adventure RPG epic sits comfortably among the illustrious alumni of the best games of all time and with good reason. Geralt’s poignant and tumultuous journey through a vibrant, detailed fantasy world is only outdone by the quality of the narrative, whereby he must track down his adopted daughter, Ciri while fighting off hordes of otherworldly demons, trolls, monstrosities, and so on. The irreverent humor, the cast of vibrant characters, multiple endings, and the quality of combat, make for an all-around immersive and compelling experience.
Grand Theft Auto V
Rockstar’s longrunning gangster simulator series entered new territory with Grand Theft Auto V. With a world designed as a playground for our most murderous and mischievous impulses, Los Santos and the surrounding area is oozing with criminal potential. The three-pronged hero gameplay is also innovative and fits perfectly with a sweeping story that depicts the unraveling of three men in their search for riches, and meaning, in what is a fame-hungry, money-grabbing cesspit of crooks and swindlers.
Far Cry 5
Far Cry 5 is all about riding a fictionalized version of Montana from the grip of a crazy cult of doomsday naysayers led by a lunatic. Sounds good, right? Factions, an arsenal of colorful weapons, and an expansive open world prop up Far Cry 5 as arguably the best in the franchise. Half-RPG, half-action adventure, few games rival the irreverence of one of Ubisoft’s flagship franchises. It’s also one pretty game, perfect for SLI scaling.
The battle royale game that spearheaded a phenomenon that has since spread to all corners of the gaming world, PUBG, as its colloquially known, is a game of wits, deft aim, and frantic gunfights. Although superseded by Fortnite, it retains its crown as the more realistic of the BR games and its position among the most played game on Steam.
Dark Souls III
The closing chapter in a trilogy known for being among the most challenging gaming experiences around, Dark Souls III is an action RPG about a rising tide of undead creatures taking over a fantasy medieval world. You’ll die countless times in your quest to prevent the incoming age of dark by stopping the first flame from dying out. Enemies are smart, adaptive, and bolstered by changing attack patterns. Unforgiving and iconic, Dark Souls III is worth any gamer’s time.
Although much of our attention is now honed in on Bethesda’s first foray into survival multiplayer with Fallout 76, Fallout 4 remains the most recent single-player Fallout game to date. Players gallivant across a post-apocalyptic world teeming with nuclear-induced aberrations as terrifying as the next while unpicking the rich lore that courses through the series. The RPG elements that define the franchise are back and better than ever. You also get a dog as a sidekick.
Metal Gear Solid V: The Phantom Pain
The latest Kojima made MGS game, Metal Gear Solid V: The Phantom Pain is a fitting homage to two decades of Snake’s stealthy adventures through many locales, fending off colorful enemies, and does so in style, set before much of the events of the previous games, this time landing players in far off Afghanistan and Angola. Big guns, seemingly unwinnable odds, and packed full of emotion, Metal Gear Solid V: The Phantom Pain merits the praise showed on the title from pundits across the board.
League of Legends
Dota 2’s playful little brother, League of Legends, is a worldwide phenomenon with reportedly over 60 million unique monthly players across the globe. With what is arguably the biggest eSports scene in the world, it’s hard to disagree with how easy League of Legends is to pick up and enjoy. Not the hardest MOBA around, League’s numbers don’t lie, and a steady stream of new heroes keep the game fresh and exciting.
Assassin’s Creed IV Black Flag
Assassin’s Creed isn’t for everyone, that much we can agree on, notably as Ubisoft churns out yearly iterations with very little innovation, barring the most recent Origins, and Odyssey. However, among a lukewarm catalog, Assassin’s Creed IV Black Flag stands as an exception. The naval warfare and piracy in Black Flag make the game. No wonder copycat games like Sea of Thieves and the upcoming Skull & Bones borrow heavily from the same template and explore a similar formula.
World of Warcraft
The MMORPG rules them all. More content that you could ever want, PvP, PvE, and a vast world all set in a fantasy world brimming with Warcraft lore and depth. Although showing signs of its age, the latest Battle For Azeroth DLC injects new life into a game that still attracts ten of thousands of players on a daily basis. Most cards run World of Warcraft with no trouble at all, so SLI is overkill, but back in the day, it proved a great way to reveal the beauty of Blizzard’s most ambitious game to date.
Tom Clancy’s Rainbow Six Siege
A multiplayer game through and through, Tom Clancy’s Rainbow Six Siege is among the most finely tuned FPS games around. Tactical, intense, and cerebral, no wonder the game is among the most exciting eSports to watch. The realism is also worth noting; one false move and death comes quickly.
The latest edition of Blizzard’s seminal hack and slash isometric RPG is a fitting homage to the original two titles that released around the turn of the century. Spruced up graphics as well as the same classic choice of classes and a world crawling with a vibrant selection of enemies make for a great single-player experience and even better co-op game to be played with friends for hours on end.
The Elder Scrolls V: Skyrim
Skyrim needs no introduction. Although Bethesda merits a lot of the criticism thrown its way, no one can argue that the developer can’t make a phenomenal open-world RPG.
Tom Clancy’s The Division
Middle Earth: Shadow of War
Rise of the Tomb Raider
Batman: Arkham Asylum
Batman: Arkham City
Call of Duty: Black Ops II
Age of Empires III
Beyond Good & Evil
Command & Conquer 3: Tiberium Wars
Fable: The Lost Chapters
Final Fantasy XI
Gears of War
Path of Exile
Resident Evil 6
Silent Hill 3
XCOM: Enemy Unknown
XCOM: Enemy Within