PCI Express 4.0 has been ratified as a standard by the PCI SIG. This now means that motherboards, chipsets and processors all have to be modernized to be able to use the improved bandwidth. Generally PCI Express improvements follow the semiconductor sector improvements with incremental change.
PCI Express 4.0 is backwards and forwards compatible with earlier standards.
PCI Express 4.0 offers a transfer rate of 16 GT/s with flexible lane width configurations, providing significant I/O performance benefits useful for storage, networking, and AI applications. At the same time, PCI-SIG has targeted Q2 2019 for releasing the finalized PCI Express 5.0 specification, so PCIe 4.0 PCI Express 4.0 won’t be quite as long-lived as PCIe Express 3.0 has been.
In context, PCI-SIG has previously kept to a four year cadence for PCI Express 1.0 (2003), PCI Express 2.0 (2006), and PCI Express 3.0 (2010).
The rising demands of AI compute workloads, PCI Express NVMe and 3D XPoint storage, and networking speeds, particularly as 10Gb Ethernet becomes more and more accessible to consumers.
NVIDIA has already jumped the gun with their expanded SLI connector for dual card setups. PCI Express 4.0 can provide more bandwidth for such requirements.
Testing for interoperability should not take long at all. Consumer motherboards should appear in the fall of the year.