Difference Between Crossfire and SLI

Crossfire vs. SLI

Crossfire and SLI (Scalable Link Interface) are two proprietary methods of connecting multiple video cards to make them work together, thereby improving their performance. These multi-GPU configurations can be helpful in gaming, where the graphical needs can be quite high. Instead of buying an expensive high-end card, you can use two cheaper low-end cards to match or exceed their performance, or use two high-end cards for even better performance. The main difference between the two is the companies that developed them. SLI is from Nvidia, and can only be used with Nvidia cards, while Crossfire is only for ATI cards.

Nvidia was the first to release SLI as a multi-GPU technology. ATI created Crossfire as competition as soon as the advantages of using two or more cards became apparent. Both multi-GPU systems work by dividing the workload between the video cards. This is achieved by either dividing each frame into two, and then assigning each one to a different card, or by assigning each full frame to a different video card. The first mode is called SFR (Split Frame Rendering) for SLI, or Scissors for Crossfire, and the second mode is called AFR (Alternate Frame Rendering) for both. A third mode uses a combination of both with the use of four video cards. Crossfire has an extra mode called SuperTiling, which is not present in SLI enabled cards. Under this mode, the frame is divided into 32×32 pixel tiles, which are then assigned to individual video cards.

The major limitation for multi-GPU processing is the need to have identical cards. SLI has made a bit of an improvement in this area, allowing cards that are based on the same GPU to work together. Crossfire takes this a step further by allowing cards with different graphics chips to work together, as long as they belong to the same family.

If you want to go with a multi-GPU system, you do not really have the option to choose whether you will use Crossfire or SLI, as it will depend on what video card you like to use. If you opt for a Nvidia card, then you are stuck with SLI, and the same is true for ATI and Crossfire.

Summary:

1. Crossfire is exclusive to ATI products, while SLI is for Nvidia.

2. Crossfire adds an extra mode that is not found in SLI.

3. Crossfire is more tolerant when using different video cards compared to SLI.

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