The official version of PCI-E 4.0 specification is here! Bandwidth doubled again

At the Hot Chips conference, PCI-SIG said it would approve the new specification by the end of 2017, which will be updated from version 0.9 to version 1.0. The update cycle of the first three generations of PCI-E was about 3 to 4 years. PCI-E3.0 was first unveiled in 2010, and it took 7 years for PCI-E 4.0 to be released.

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PCI-SIG attributes the 7-year upgrade cycle to the stagnation of industry development. The PCI-E 3.0 bandwidth is sufficient to meet the data throughput requirements of current storage, network, graphics cards and other devices. But ironically, the development of artificial intelligence has made a big leap in the past two years, resulting in insufficient PCI-E 3.0 throughput. Storage devices also use the NVMe protocol, all PCI-E channels, and network bandwidth has also increased, making PCI-E 3.0 bandwidth stretched.

PCI-SIG has stated that the official version of PCI-E 4.0 will be released before the end of the year. The features of PCI-E 4.0 have been completed and will soon enter the IP review stage. Currently, some manufacturers have launched 16GT/s controllers, but the PCI-E 4.0 specification is version 0.9, which is still far from the final version 1.0.

PCI-SIG also stated that they are accelerating the development and feedback process, while simplifying early specification revisions to shorten the release date. PCI-E 4.0 is actually a transitional version, because PCI-SIG will launch the PCI-E 5.0 specification with double the speed in 2019. Now the PCI-E 5.0 specification has been revised to version 0.3 and is expected to be released in the fourth quarter of this year.

Currently, the bandwidth of PCI-E 4.0 is 64GB/s, and PCI-E 5.0 will reach 128GB/s. These two PCI-E versions still use the 128b/130b standard encoding scheme of PCI-E3.0. This scheme will save 20% of R&D costs, and further encoding can reduce expenses by 1.5%.

PCI-SIG defines the specifications, but the organization cannot decide when the terminal products will be available on the market. AMD and Intel are the main drivers of PCI-E 4.0. AMD platform will use PCI-E 4.0 in 2020, and Intel is also stepping up the deployment of their Optane hard drive strategy.