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

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).

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.