Terminology » PCIe 2.0 vs 3.0 vs 4.0 vs 5.0: A Detailed Comparison

PCIe 2.0 vs 3.0 vs 4.0 vs 5.0: A Detailed Comparison

pcie pcie comparison data transfer interconnect bandwidth computer interface

This page details the differences between PCIe Gen 2, PCIe Gen 3, PCIe Gen 4, and PCIe Gen 5.

Introduction to PCIe

  • PCIe stands for Peripheral Component Interconnect Express.
  • It’s a high-speed serial computer expansion bus designed to replace older PCI/PCI-X standards.
  • PCIe is the successor to the traditional PCI interface in desktop PCs.
  • PCIe has evolved through versions 1.0, 2.0, 3.0, 4.0, 5.0, and a planned 6.0.
  • These versions offer varying raw data rates (speeds) and bandwidths.
  • The latest versions support maximum data rates up to 32 GT/s and interconnect bandwidths of 32 Gb/s.
  • It uses a serial interface, unlike the parallel interface of PCI.
  • PCIe supports more devices (approximately 32) per bus compared to PCI (around 5).

PCIe, PCI Express

The PCIe interface supports hot-plugging and uses a point-to-point or shared switch topology. The figure above shows the serial interface connection used by PCIe devices to communicate with the switch.

PCIe 1.0 | PCIe Gen 1

Here’s a rundown of the features of the PCIe 1.0 or PCIe Gen 1 interface:

  • Introduced in 2003.
  • Uses 8b/10b line coding.
  • Supports a transfer rate of 2.5 GT/s (approximately 2.5 Gbps). This is the encoded serial bit rate.
  • Offers an interconnect bandwidth of 2 Gb/s.
  • Provides a throughput of 250 MB/s. Throughput is the pre-coded data rate before encoding, also known as “Bandwidth Lane Direction.”
  • Supports a total bandwidth of approximately 8 GB/s for an x16 link.

PCIe 2.0 | PCIe Gen 2

The PCIe 2.0 or PCIe Gen 2 interface includes the following features:

  • Introduced in 2007.
  • Employs 8b/10b line coding.
  • Supports a transfer rate of 5.0 GT/s.
  • Offers an interconnect bandwidth of 4 Gb/s.
  • Provides a bandwidth lane direction of approximately 500 MB/s.
  • Supports a total bandwidth of approximately 16 GB/s for an x16 link.

PCIe 3.0 | PCIe Gen 3

Key features of the PCIe 3.0 or PCIe Gen 3 interface:

  • Introduced in 2010.
  • Uses 128b/130b line coding.
  • Supports a transfer rate of 8.0 GT/s.
  • Offers an interconnect bandwidth of 8 Gb/s.
  • Provides a bandwidth lane direction of approximately 1 GB/s.
  • Supports a total bandwidth of approximately 32 GB/s for an x16 link.

PCIe 4.0 | PCIe Gen 4

The PCIe 4.0 or PCIe Gen 4 interface offers the following:

  • Introduced in 2017.
  • Uses 128b/130b line coding.
  • Supports a transfer rate of 16.0 GT/s.
  • Offers an interconnect bandwidth of 16 Gb/s.
  • Provides a bandwidth lane direction of approximately 2 GB/s.
  • Supports a total bandwidth of approximately 64 GB/s for an x16 link.

PCIe 5.0 | PCIe Gen 5

Here’s a look at the features of the PCIe 5.0 or PCIe Gen 5 interface:

  • Introduced in 2019.
  • Backward compatible with previous PCIe Gen 1/2/3/4.
  • Uses 128b/130b line coding.
  • Supports a transfer rate of 32.0 GT/s.
  • Offers an interconnect bandwidth of 32 Gb/s.
  • Provides a bandwidth lane direction of approximately 4 GB/s.
  • Supports a total bandwidth of approximately 128 GB/s for an x16 link.