Peripheral Component Interconnect Express (PCIe)

• 1-bit serial bus called lanes
• Up to 32 independent serial lanes
• 250 MBps throughput per lane (8 GBps for 32x)
• Connects directly to the northbridge like AGP
• PCIe 2.0 doubles the throughput

Peripheral Component Interconnect (PCI)

• Comes in both 32 and 64-bit bus widths
• 3.3V and 5V volts but mostly 3.3V now
• Came in 33 and 66 MHz speeds
• Up to 532 MBps throughput (64-bit, 66 MHz PCI 2.1)
• Slots are colored white

Accelerated Graphics Port (AGP)

• Used exclusively for graphics cards
• 32-bit wide data bus
• AGP bus connects to the northbridge
• Up to 2.1 GBps throughput (AGP 8x)
• Multipliers enable AGP devices to operate between bus clock cycles
• Used multiplier settings of 1x, 2x, 4x, 8x
• 3.3V, 1.5V, 0.8V depending on AGP revision
• Slots are typically brown

Extended Industry Standard Architecture (EISA)

• 32-bit wide data bus
• Found on older ATX and AT motherboards
• Ran at 8.33 MHz
• Obsolete

Industry Standard Architecture (ISA)

• 8 and 16-bit wide buses
• Ran at 4.77 MHz (8-bit) and 6-8 MHz (16-bit)
• Found on older XT and AT motherboards
• Obsolete

Micro Channel Architecture (MCA)

• Proprietary interface and bus architecture
• Used on old IBM PS/2 systems
• 32-bit wide data bus
• Up to 66MBps throughput
• 10 MHz bus speed
• Obsolete

Audio/Modem Riser (AMR)

• A special expansion slot for audio and modem cards
• Found on older ATX boards
• Superseded by CNR

Communications and Network Riser (CNR)

• A special expansion slot for modems and network interface cards
• Found on some older ATX boards but not new ones
• Still found on some microATX boards