Scan-Line Interleave

Not to be confused with Scalable Link Interface.

Scan-Line Interleave (SLI) is a multi-GPU method developed by 3DFX for linking two (or more) video cards or chips together to produce a single output. It is an application of parallel processing for computer graphics, meant to increase the processing power available for graphics.^[1][2]

Scan-Line Interleave

Voodoo2 with SLI cable at top left
Manufacturer	3DFX
Type	Multi-GPU technology
Release date	1998
Connectivity	Ribbon cable
Successor	Scalable Link Interface

3DFX's SLI technology was first introduced in 1998 with the Voodoo2 line of graphics accelerators. The original Voodoo Graphics card and the VSA-100^[3][4] were also SLI-capable. However, in the case of the former, it was only used in arcades,^[5][6] as well as professional applications via Primary Image's Piranha^[7][8][9] card, intended for use with simulations using various^[10][11] graphics APIs such as OpenGL, Glide, or Primary Image's own Tempest API. Support for the MultiGen OpenFlight Format in particular was specifically advertised.^[7][10][11]

NVIDIA reintroduced the SLI acronym in 2004 as Scalable Link Interface. NVIDIA's SLI, compared to 3DFX's SLI, is modernized to use graphics cards interfaced over the PCI Express bus.^[12]

Function

A single PCI video card from Quantum3D that combines two Voodoo2 boards in SLI configuration

3DFX's SLI design was the first attempt, in the consumer PC market, at combining the rendering power of two video cards. The two 3DFX cards were connected by a small ribbon cable inside the PC. This cable shared graphics and synchronization information between the cards. Each 3DFX card rendered alternating horizontal lines of pixels composing a frame.^[1][2]

See also

• Scalable Link Interface - Nvidia
• AMD CrossFireX - AMD