What is SLI Good For? Unpacking the Legacy of NVIDIA’s Multi-GPU Technology
At its core, **NVIDIA’s Scalable Link Interface (SLI)** was designed to deliver significantly enhanced graphics performance by linking multiple **GeForce GPUs** together. The idea was simple: instead of relying on a single graphics card, you could harness the power of two, three, or even four GPUs working in tandem. This theoretically translated to higher frame rates, better visuals, and a smoother gaming experience, especially at higher resolutions and settings. In essence, SLI aimed to provide a way for enthusiasts and gamers to achieve the highest possible level of graphical fidelity by effectively combining the processing power of multiple GPUs.
However, the reality of SLI was often more complex than the initial promise. While some games and applications saw substantial performance gains, others experienced minimal improvements, or even performance degradation. This inconsistency, along with other factors, eventually led to SLI’s decline. Despite its current status, understanding what SLI was initially intended for and its implications is crucial to understanding the landscape of PC gaming hardware.
The Intended Benefits of SLI
The primary objective of SLI was to **boost rendering performance** by distributing the workload across multiple graphics cards. This meant that instead of one GPU bearing the entire burden of rendering a scene, the task was divided. Here are some key benefits it aimed to deliver:
Increased Frame Rates
The most sought-after benefit of SLI was the potential for significantly **higher frame rates**. By leveraging the combined processing power of multiple GPUs, gamers hoped to achieve smoother gameplay, particularly in graphically demanding games. In ideal scenarios, SLI could provide a noticeable bump in FPS, making games more enjoyable and responsive.
Enhanced Visual Fidelity
Beyond frame rates, SLI also aimed to improve the overall visual quality of games. With more GPU power at their disposal, gamers could push graphical settings to their limits, enabling higher resolutions, better texture quality, and more complex visual effects. This resulted in a more immersive and visually appealing gaming experience.
Support for High-Resolution Gaming
Running games at high resolutions like 4K or even 8K can be incredibly taxing on a single GPU. SLI provided a way to make these resolutions more achievable by distributing the workload. This was especially important for those seeking the best possible gaming experience on high-resolution monitors and displays.
Streaming Capabilities
One of the practical applications of SLI was its potential benefit for streaming. By having a dedicated GPU to render the stream while another handled the game, frame drops and performance issues during live broadcasting could be minimized. This made SLI an appealing option for streamers who wanted to maintain a smooth and consistent stream while playing demanding games.
The Challenges and Limitations of SLI
Despite its promising potential, SLI faced several challenges that ultimately led to its decline. These limitations included:
Inconsistent Performance
The biggest issue with SLI was that it did not always deliver consistent performance gains. In many games, the scaling was poor, meaning that adding a second or third GPU didn’t result in a proportional increase in performance. Some titles even showed a slight decrease in frame rates with SLI enabled.
Micro-stuttering
Another common issue with SLI was **micro-stuttering**. This occurred when frames were not rendered consistently, leading to noticeable hiccups and uneven animation, which impacted the smoothness of gameplay. While some micro-stuttering issues could be minimized with driver updates, it remained a persistent problem.
Driver Conflicts and Compatibility Issues
SLI configurations were notorious for driver conflicts and compatibility issues. Because of the way SLI was implemented in hardware and relied on specific driver setups, it often made it hard for game developers to tailor the multi-GPU experience. Consequently, certain games would not support SLI effectively, or could experience glitches and instability. The need for consistent driver updates also added to the management overhead of multi-GPU setups.
Increased Power Consumption and Heat Output
Running multiple GPUs in SLI also resulted in significantly higher power consumption and heat output, increasing your energy bill and requiring robust cooling solutions. This was a significant drawback for those who were concerned about energy efficiency or had limited space for cooling. While this increased performance, it came with other complications.
Lack of Support from Developers
Over time, game developers began to move away from explicit support for SLI due to the complexities involved and the relatively small percentage of users who utilized multi-GPU setups. As such, developers found it more efficient to optimize games for single-GPU systems, marking the beginning of the end for SLI.
The Legacy of SLI
While SLI is no longer the mainstream technology it once was, it played a significant role in the evolution of PC gaming. It pushed the boundaries of graphical performance and highlighted the potential of multi-GPU computing. Its decline led to a shift towards single-GPU dominance and innovations like **DLSS and ray tracing**, which provide performance enhancements without the complexities of multi-GPU configurations.
Today, gamers are generally advised to invest in a single powerful GPU instead of relying on SLI, as it provides a more consistent and reliable experience. However, understanding the history and purpose of SLI is valuable for understanding the progress of graphics technology.
Frequently Asked Questions About SLI
1. What is Scalable Link Interface (SLI)?
SLI is a multi-GPU configuration technology developed by NVIDIA that allows multiple graphics cards to work together to render graphics, aiming to increase performance.
2. Did SLI always improve performance?
No, SLI didn’t always guarantee improved performance. Some games saw significant performance gains, while others experienced minimal improvements or even decreased performance.
3. Why is SLI no longer widely used?
SLI is no longer widely used due to the inconsistencies in performance, compatibility issues, and the complexity of implementing it correctly. Also, GPU manufacturers are focusing more on improving single-GPU performance.
4. Is a single better GPU better than SLI?
Yes, in most cases, a single powerful GPU will provide a better and more reliable experience than an SLI configuration. It avoids the pitfalls of poor scaling and micro-stuttering associated with SLI.
5. What is micro-stuttering in SLI?
Micro-stuttering refers to the uneven rendering of frames, which can cause noticeable hiccups and stutters during gameplay, making it feel less smooth.
6. What were some of the drawbacks of SLI?
Drawbacks of SLI included inconsistent performance, micro-stuttering, driver conflicts, compatibility issues, increased power consumption, and heat output.
7. What GPUs support SLI?
Most modern NVIDIA GPUs no longer support SLI. The last cards to have it were the RTX 3090. Most of the 30 series cards do not support SLI.
8. Can you mix different GPUs in an SLI configuration?
While it was technically possible to mix cards with the same GPU chip, it was highly recommended to use identical video cards for optimal performance and stability.
9. What replaced SLI?
**NVLink** has effectively replaced SLI due to its higher bandwidth and more efficient multi-GPU operation for certain professional workloads. However, for gaming, the focus is now on improving single GPU performance.
10. What happened to NVIDIA’s SLI driver support?
NVIDIA ended the support for adding new SLI profiles to its driver with the RTX 20 Series GPUs (and earlier) on January 1st, 2021. Focus has shifted to developers implementing SLI support directly within their games.
11. How many monitors can an SLI setup support?
Each GPU in an SLI setup can typically support two monitors, meaning a dual-GPU setup could support up to four monitors in total.
12. Did SLI help with streaming?
Yes, SLI could be beneficial for streaming. A dedicated GPU for rendering the stream could prevent frame drops and maintain smooth gameplay.
13. How do you know if SLI is working?
You can confirm if SLI is working through the NVIDIA Control Panel by selecting “Set SLI configuration” under 3D Settings. Additionally, you can enable the “Show SLI Visual Indicator” to see a visual confirmation on the screen.
14. Is AMD CrossFire the same as NVIDIA SLI?
AMD CrossFire was the competitor to SLI, providing multi-GPU functionality for AMD GPUs. While the functionality is similar, CrossFire also faced similar issues and is not a common technology.
15. What games support dual GPU?
Some games that historically supported multi-GPU configurations (though not always well) include *Deus Ex: Mankind Divided, Rise of the Tomb Raider, Sniper Elite 4, Ashes of the Singularity, Strange Brigade* and various *Hitman* titles.