The PCI slot on your motherboard is fast becoming superseded. It is being replaced by the PCI express slots. This will eventually mean than all your old cards will not fit into the new slots.

PCI express comes in a few varieties - 1x, 2x, 4x, 8x, 16x and 32x. The longer the slot, the faster the card. At the moment, 16x PCI Express graphics cards are pretty common.


PCI 1 Gbps
AGP 8X 17 Gbps
PCI Express 1x 2.5 [5]* Gbps
PCI Express 2x 5 [10]* Gbps
PCI Express 4x 10 [20]* Gbps
PCI Express 8x 20 [40]* Gbps
PCI Express 16x 40 [80]* Gbps
PCI Express 32x 80 [160]* Gbps
IDE (ATA100) 0.8 Mbps
IDE (ATA133) 1 Gbps
SATA 2 3 Gbps

*Dual direction

Gbps: Giga bits per second, (1,000,000,000 bps).
Mbps: Mega bits per second - (1,000,000 bps).
Byte: is 8 bits


PCI Express 1x Slot


PCI Express 16x Slot

Further Reading