What Is SLI & how does it work? Best Guide 2023

In this article, is have given all the details related to the most asked question which is what is SLI. So, Nvidia’s Scalable Link Interface technology allows the use of many graphics cards in tandem to generate a single output. This technique is an implementation of the parallel processing principle, and it significantly improves performance for graphically heavy applications like as games and 3D rendering. SLI allows several graphic processing units (GPU) to collaborate in order to accelerate processing and share burden while producing a scene.

The following items are required for the setup:

• A motherboard that supports SLI
• At least two Nvidia graphics cards of the same kind that are SLI compatible.
• An SLI Bridge adapter

An SLI-compliant board will already have the requisite two PCIe x16 slots. Both cards are linked together using a special SLI bridge connection.

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Uses of Scalable Link Interface (SLI)

SLI works by assigning distinct chunks of the same picture to each GPU. The master card is often given the upper part of the scene, while the slave is given the lower half. When the slave GPU completes rendering the second half of the scene, it sends it to the master GPU to be merged before being delivered to the display.

When SLI was initially introduced in 2004, it was only supported by a few motherboard types, and setting it up was a time-consuming process. Because motherboard designs at the time did not have enough PCIe bus, SLI compatible boards came with a “paddle card” that was fitted between the two PCIe slots and could channel all lanes into the primary slot or split them evenly between the two slots depending on its location.

As technology advanced, the paddle card became obsolete. SLI may now be accomplished with a single graphics card by combining two different GPUs on a single board, removing the requirement for two PCIe slots or a SLI compatible motherboard. Quad SLI may be achieved by utilizing two of these dual GPU cards on a SLI motherboard.

SLI was developed in response to our ever-increasing demand for graphics processing capability. Because hardware technology cannot keep up with processing needs, the ideal solution is to harness current technology in parallel processing and have numerous GPUs work together to accelerate processing. The outcome is a significant increase in performance, but it comes at a cost because at least two of each card are required.

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However, because the two cards do not operate independently of one another, the performance improvement is not complete. The master card must still wait for the slave to finish before combining what both have done before transmitting it to be shown, which is the system’s bottleneck. It must take a bit longer to merge the renderings, resulting in a real-world performance boost of 60-80%, which is still a significant increase.

Hardware Required to Run SLI

Explaining about the topic of what is SLI and what is needed to make it work properly with a real-life example, I will you tell you an event that happened to my Friend. My friend destroyed his motherboard because he assumed that because he had enough slots, he could just attach graphics cards and load up the machine. That was my fault. However, there are a few more needs than a handful of PCI-Express x16 slots.

First, determine whether the motherboard is SLI-compatible. This is a critical step, so proceed with caution, especially because some motherboards enable SLI, CrossFire, both, or none. Cards may be configured to function in SLI mode if you only want to use two cards.

Second, you must have identical graphics cards. They must be the same model and series, however they might come from different manufacturers. Despite their similarities, connecting a GTX 1080 and a GTX 1070 will not work.

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For example, if one is built by MSI, another by ASUS, and the third by Gigabyte, you may still setup them on the same PC. On rare circumstances, “mixed SLI” setups can be operated on some cards that only have a matching core codename, such as G70, G73, G80, and so on.

Configuration of a Master-Slave System

Graphics cards are configured in a master-slave arrangement, which implies that one card will act as the “master” even though the workload is split evenly across all cards. The master will control the top half of the screen in a two-card arrangement, while the slave will manage the bottom half. When the slave has finished rendering its portion of the screen, it transmits it to the master, who then merges the two renderings and delivers it to the monitor.

When the cards are mismatched, the slower or poorer card takes over, with the better card adapting by running at the same speed as the other card or removing its additional memory.

Bridges/Connectors for SLI

The graphics cards are linked together using SLI Bridge. It’s also known as the SLI Connector because its purpose is to link the cards directly. It’s worth mentioning that simply using the motherboard’s chipset, you can run two low-end or mid-range cards without requiring the bridge.

This is also feasible but not advised for high-end GPUs. Because the chipset lacks sufficient memory, the outcomes will be disastrous. This is where SLI Bridge comes in handy, since it minimises bandwidth limits and allows data to be sent directly across cards.

SLI Bridges are classified into three types:

• Standard Bridge (400 Mhz Pixel Clock, 1GB/s bandwidth) – This is a standard bridge that comes with motherboards that enable SLI up to 19201080 and 25601440@60 Hz.
• LED Bridge (540 MHz Pixel Clock) – Recommended for 25601440@120 Hz+ and 4K displays. NVIDIA, EVGA, MSI, ASUS, and others sell it. It can only run at a higher Pixel Clock if the GPU supports it.
• High-Bandwidth Bridge (650 MHz Pixel Clock and 2GB/s Bandwidth) – This is the quickest bridge and is only available from NVIDIA. It is suited for 5K displays and surrounds. SLI HB Bridges come in just two-way configurations.

While the two-GPU configuration is probably the most common, SLI can also be built in a three or four GPU dynamic by utilising either a single bridge that links every card or by merging two two-way bridges. Combining three or four dual cards with a 2-way bridge is impossible since hexa- or octa-SLI technology does not exist.

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NVIDIA is phasing down support for more than two-card combos owing to high driver complexity. Indeed, GPUs like the GTX 1070, GTX 1080, and upwards only enable two-way SLI.

All Windows versions after Windows Vista, including 32-bit and 64-bit, support SLI. It can also be modified to run on Linux, but there aren’t many high-end graphics video games available for that platform, so it’s not worth the effort.

SLI requires a minimum of 2 GB of RAM for a 32-bit system and 4 GB for a 64-bit system. NVIDIA ForceWare Unified Driver Architecture (UDA), which includes support for SLI technology, was introduced in 2003. As a result, no additional SLI-specific drivers are required, although they are still required for each graphics card.

Energy Requirements

Because GPUs take a lot of power and you’ll be operating two or more at the same time, you’ll need an extremely strong and dependable Power Supply Unit. Be warned that high-end graphics cards can consume up to 200-350 watts of electricity.

It is important to note that not all games and programmers support SLI. NVIDIA offers SLI profiles in their driver package for those that do, so you don’t have to set anything up manually to get a better gaming experience.

Split Frame Rendering in SLI Modes

SFR analyses the produced image to distribute the workload among the GPUs. Depending on the shape, the frame is split on a horizontal line to do this. If the upper section of the screen merely draws the sky, for example, this line will be lower to balance off the geometry demand on the GPUs.

Rendering of an Alternate Frame

AFR denotes that each frame is rendered by a separate GPU. In reality, this is frequently accomplished by having one card work on odd frames and the other work on even ones.

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Although AFR has a higher frame rate than SFR, it can create micro stuttering, which alters the perception of frame rate. While the frequency with which frames come can be increased, the creation time of the frames is not, hence the input lag cannot be reduced.

Adjustments of SLI Bridges

If you have two low or mid-range GPUs, you should be able to combine them using your motherboard’s chipset. Unfortunately, when merging two high-end GPUs, this isn’t the best approach. Most motherboard chipsets lack the RAM necessary to maximise the performance of the coupled cards.

In these circumstances, a SLI bridge is required.

These bridges, often known as SLI connections, are available in three configurations:

• Standard
• LED
• High-Bandwidth

Any motherboard that supports SLI screens of 19201080 and 25601440@60 Hz should be able to use the standard. To get the most out of SLI on a 4K display, you’ll need an LED bridge. Nvidia presently sells high-bandwidth bridges that only allow 2-way SLI systems. They’re perfect for high-end monitors with surround or 5K screens.

Checklist for SLI compatibility.

When someone ask what is SLI and its compatibility, I will say that SLI enables the power of two or more GPUs to be combined, making it perfect for gaming and high-end graphics design work. The technique also enables the combination of cheap and mid-range GPUs to do the same tasks as a more expensive high-end alternative.

It is, however, not a plug-and-play technology. To make the technology function, you must have a suitable motherboard and numerous SLI-compliant GPUs of the same model.

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GPUs with SLI Support

With a few exceptions, almost all SLI-capable GPUs are part of Nvidia’s GeForce lineup. Every card that supports SLI is an Nvidia card, but other manufacturers, such as AMD, provide comparable principles without the SLI moniker. For example, AMD’s Crossfire technology works similarly to SLI on AMD cards. There is no cross-compatibility between manufacturers.

Despite the fact that all SLI-compatible GPUs are labelled Nvidia, not all Nvidia cards enable SLI. All currently supported cards are listed below:

1. GeForce RTX 3090
2. GeForce RTX 2080 Ti
3. GeForce RTX 2080 SUPER
4. GeForce RTX 2080
5. GeForce RTX 2070 SUPER
6. Nvidia Titan Xp
7. Nvidia Titan X (Pascal 2016 release)
8. GeForce GTX 1080 Ti
9. GeForce GTX 1080
10. GeForce GTX 1070
11. GeForce GTX TITAN X
12. GeForce GTX 980 Ti
13. GeForce GTX 980
14. GeForce GTX 970
15. GeForce GTX 960
16. GeForce GTX 950
17. GeForce GTX TITAN
18. GeForce GTX 780 Ti
19. GeForce GTX 780
20. GeForce GTX 770
21. GeForce GTX 760 Ti
22. GeForce GTX 760
23. GeForce GTX 690
24. GeForce GTX 680
25. GeForce GTX 670
26. GeForce GTX 660 Ti
27. GeForce GTX 660
28. GeForce GTX 650 Ti BOOST
29. GeForce GTX 480
30. GeForce GTX 470
31. GeForce GTX 465
32. GeForce GTX 460
33. GeForce GTX 460 SE
34. GeForce GTS 450
35. GeForce GTX 555 (OEM)
36. GeForce GTX 560 Ti (OEM)
37. GeForce GTX 560
38. GeForce GTX 550 Ti
39. GeForce GTX 590
40. GeForce GTX 560 Ti
41. GeForce GT 545 GDDR5
42. GeForce GTX 570
43. GeForce 9800 GT
44. GeForce GTX 580
45. GeForce 9600 GT
46. GeForce 8500 GT
47. GeForce 8600 GTS
48. GeForce 8600 GT
49. GeForce 8400 GS
50. GeForce GTX 275X
51. GeForce GTS 150
52. GeForce GT 130
53. GeForce GT 120
54. GeForce GTS 250
55. GeForce GTX 285
56. GeForce GTX 295
57. GeForce 8800 ULTRA
58. GeForce GTX 280
59. GeForce 8800 GTX
60. GeForce 9800 GX2
61. GeForce GTX 260
62. GeForce 9400 GT
63. GeForce 9500 GT
64. GeForce 9800 GTX
65. GeForce 9800 GTX+

Conclusion:

If you’re seeking answer about what is SLI and is it worth to buy, look no further. SLI is worthwhile, but you must remember that it will only improve your gaming experience if you have a compatible configuration.

Keep in mind that your computer’s components communicate with one another. Installing a SLI to handle multiple GPUs will be ineffective if your CPU is not capable of supporting multiple GPUs at the same time. Why? GPUs require a lot of energy, which means they’ll generate a lot of heat.

Your computer may overheat fast if it is not properly aired or cooled. Simply said, you’ll be able to run high-quality game visuals for around an hour before your PC shuts down due to tiredness.

As a result, if you acquire a SLI, make sure the rest of your PC has been upgraded as well so they perform well together. It should also be noted that the games themselves have a graphical restriction. Even though your PC is capable of generating high-quality visuals, if the game is designed to give a lower limit, your additional GPU will be ineffective.

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