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.

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.

[7][10][11] NVIDIA reintroduced the SLI acronym in 2004 as Scalable Link Interface.

[12] 3DFX's SLI design was the first attempt, in the consumer PC market, at combining the rendering power of two video cards.

Each 3DFX card rendered alternating horizontal lines of pixels composing a frame.