The PCIe 3.0 standard was a major update for the PC industry and doubled the bandwidth available for devices using PCIe lanes. While this available bandwidth proved to be more than enough for most mainstream uses (and probably why we did not see any update for over 7 years) since its ratification in 2011, the time has come for a new standard to launch soon.
PCIe 4.0 landing before the end of 2017, will be succeeded by 5.0 in 2019
The story originates from our colleagues over at Tom's Hardware and a recent discussion with PCI-SIG. The organisation has promised that the PCIe 4.0 spec will land before the end of 2017 and in fact we will even be seeing devices before the year is over. This is because many manufacturers have already moved forward with the 0.9 revision instead of waiting for the 1.0 revision.
PCIe 4.0 to land soon, and PCI-SIG assures us it will ratify the new specification by the end of 2017. The sluggish ratification process hasn't hampered adoption entirely, though. Several IP vendors already offer 16GT/s controllers, and many vendors have already implemented PCIe 4.0 PHYs into their next-generation products. These companies are plowing ahead with the 0.9 revision of the specification, whereas the final ratified spec debuts at 1.0.
PCI-SIG says it is accelerating the development and feedback processes, along with simplifying early specification revisions, in a bid to reduce time to market for future specifications. PCI-SIG indicates that PCIe 4.0 will be a short-lived specification because the organization has fast-tracked PCIe 5.0 for final release in 2019. Tom's Hardware
The frequency speed for the x16 duplex mode has been increased to 16 GHz with PCIe 4.0 and will be further bumped to 32 GHz with PCIe 5.0. This means that the effective bandwidth will then become 64 GB/s and 128 GB/s respectively. PCIe 5.0 will also make 400 GB Ethernet solutions possible which means 50GB bw in both directions. While PCIe specs were originally designed to follow a 2 year cadence, PCI-SIG seems to have other plans, with PCIe 4.0 landing in 2017 and PCIe 5.0 following soon after in 2019. This makes it likely that some vendors might decide to skip 4.0 completely and go straight to 5.0.