Definition – What does Scalable Link Interface (SLI) mean?
Scalable Link Interface (SLI) is a computer technology launched by NVIDIA that enable multiple graphics cards to work in the single PC. It offers faster graphics performance than what is possible with the single card. Such as using two or more graphics card on the single computer may offer up to twice the performance of single video card and if each card has two GPUs, they may be four times faster the performance of the typical graphics card.
Glossary Web explains Scalable Link Interface (SLI)
In order to connect multiple graphics cards using the SLI technology, the computer must have multiple PCI express slots. The PCI express is the first video card interface that enables the connecting of several video cards because the slots share the same bus. All the previous technologies such as AGP and PCI used separate slot buses that did not allow the graphics card to be bridged together. The PCI slots must also support enough bandwidth for the cards that usually means they must be X8 or X16 slots.