What is PCIe 4.0?
PCIe 4.0 (also referred to as PCIe 4, PCIe Gen 4, PCI 4, PCI Express 4.0) is the fourth generation of Peripheral Component Interconnect Express (PCIe), high-speed computer bus technology. Designed to address applications requiring higher bandwidth at a lower cost, and for those wondering, "is PCIe 4.0 backwards compatible," PCIe 4 remains fully backwards compatible with previous PCIe generations.
The specification defines variable lane widths - x1, x2, x4, x8, x16 and x32, which gives developers access to many lane widths and speed configurations and caters to applications with various bandwidth requirements. For example, storage applications use the PCIe x4 lane widths, whereas high-performance applications that can benefit from increased bandwidths can use PCIe x16 lane widths.
A compatible PCIe 4.0 motherboard paired with a PCI gen 4 SSD can produce sequential read/write speeds twice as fast as last gen PCIe 3.0 series SSDs and more than ten times that of some of the slower SATA SSD tech.
The PCI Express 4.0 specification was finalized in October of 2017 with a published transfer (bit) rate of 16 GT/sec which is double the bit rate of the previous version, PCIe 3.0. In the table below you can see the aggregate bandwidth options offered by PCIe 3.0 vs PCIe 4.0.
|Bandwidth in GBPS||PCIE X1||PCIE X2||PCIE X4||PCIE X8||PCIE X16|