Scan Line Interleave

Scan Line Interleave ( SLI) is an inserted in the 3D computer graphics method for load distribution of the computing work across multiple graphics chips. Originally this method was developed from 1996 by 3dfx to improve performance of graphics cards the Voodoo series (especially the beginning of 1998 at the Voodoo 2 ). Scan Line Interleave here is the product name and the name of the actual procedure.

Operation

Usually two graphics cards or two GPUs are connected to each other, a card or chip calculates all the straight lines on the screen ( scanlines ), the other all the odd. Theoretically doubles as the power, but both cards must or both chips with geometry and texture information are supplied, this slows down the calculation, although, on the other hand must be after the rendering of the half- line image only half of the data written to the frame or the back buffer are or be read to the RAMDAC. At that time Voodoo 2 systems with Pentium II processor a performance increase of about 40 to 60 % could be achieved - you could raise the resolution from 800 × 600 to 1024 × 768 with the same frame rate.

In the solution with two separate 3D accelerators they are connected via a small ribbon cable, which ( is connected to the VGA monitor ) RAMDAC the first graphics card combines the two images and sends them to the monitor.

Since the Voodoo 2 only was able to calculate 3D graphics, 2D graphics, a third card must be present for normal desktop operating still, which is connected with a VGA cable loop with the first 3D graphics card. In 2D mode, the 3D graphics card only loops through the signal.

With the Voodoo 5 series 3dfx has built several SLI - capable graphics chip ( VSA -100) on a graphics card.

Graphics chips with SLI support

The following graphic chips support SLI:

Voodoo Graphics ( here it was only by the company Quantum3D cards that could be connected afterwards, all the others were limited to single tickets )
Voodoo 3 (here, however, there were only a few prototypes of Quantum3D that included four chips on a PCB)
VSA-100 (there were cards with up to 8 graphics chips on a PCB and a total of 512 MB of video RAM )

The Voodoo 2 initially always two cards were from the same manufacturer is required ( except for the Wicked3D driver). With later reference drivers and the Voodoo 2 different manufacturers worked together. The only requirement for this was the assembly with the same amount of VRAM. In Voodoo Graphics and VSA-100 SLI was only possible with video cards that were already equipped with two or more SLI -capable graphics chips.

SLI from NVIDIA

The introduced by NVIDIA in 2004 Scalable Link Interface Technology (SLI ), which also allows a pairwise operation of 3D graphics cards for the purpose of load balancing, is not based on the Scan-Line Interleave method, even if it is of use suggests the same abbreviation.

Operating / procedure: Alternate Frame Rendering | Parallel Graphics Configuation | Scan Line Interleave | Split Frame Rendering | SuperTiling

Image synthesis

ATI Multi-Rendering

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