The graphics card interface is used to exchange data between the graphics card and the computer. The interface is the contact strip for the slot. In terms of graphics card interfaces, there is the PCI bus, the AGP bus and the PCI Express.
The graphics card interfaces PCI bus, AGP bus and PCI Express differ essentially in their bandwidth and thus in the data transfer rate. In terms of development, the PCI bus (Peripheral Components Interconnect) was developed first, which therefore also has the lowest data rate. The PCI bus has various variants with higher data rates, which reach up to 10 GB/s for the PCI Express. Therefore, the PCI-Express is also most often used for graphics cards. Another graphics card interface is the AGP bus, which has a data rate of 2.1 GB/s in the fastest version.