PCIe 3.1 and 4.0 Specifications Revealed

Earlier this week PCI-SIG revealed the specifications for PCI Express 3.1 and 4.0 according to Tom’s Hardware. The PCIe 3.1 specification consolidates numerous protocol extensions into three areas of power, performance and functionality. In terms of power the PCIe 3.1 specification combines the M-PCIe and L1 power management substrates with a CLKREQ# signal. In terms of performance enhanced downstream port containment and lightweight notification protocol extensions are grouped together. In terms of functionality PCIe 3.1 bundles together precision time measurement a separate refclk with independent SSC architecture, and the process address space ID. According to PCI-SIG this specification will be released later this year, although expect some lag before we see it in new PCIe devices and system boards.Finally PCI-SIG revealed that PCIe 4.0 will have 16GT/s of transfer speed which is double that of PCIe 3.0 which has 8GT/s of transfer speed. This standard is going to come primarily for servers, workstations and high-performance computing markets and naturally retains backwards compatibility. PCIe 4.0 also provides an increase in clock rates, enabling narrower link width implementations and reduced costs through pin production. PCIe 4.0 revision 0.5 is expected in Q1 of 2014 while revision 0.9 is expected in Q1 of 2015 – so still quite some way to go yet.

Image #1 courtesy of PCI-SIG and Image #2 courtesy of RTC Magazine