The PCI SIG (Peripheral Component Interconnect Special Interest Group) has released version 1.0 of the official specification for the next PCI-Express 4.0 standard. The previous version was only a draft (version 0.9) that was under review by the technical team of the association, and therefore it is this new version 1.0 which is considered valid and official.
The new PCI-Express generation will bring double the bandwidth of the current PCIe 3.0 specification, with reduced latency, lane management and I/O virtualization capabilities. With the 1.0 specification already published, now manufacturers can start working on its implementation in their products, so it is expected that within a few months we will begin to see the first motherboards that already incorporate this new PCI-Express 4.0 standard.
Characteristics of PCI-Express 4.0
PCI-Express 4.0 will have a bandwidth of 16 GT / s per lane and per direction, twice the current 3.0 specification. An NVMe SSD that has implemented this version, for example, will have at its disposal a bandwidth of 64 Gbps (we are talking about 8,000 MB / s of maximum transfer rate). The PCI SIG has also talked about the reduction of latencies, and this has been achieved thanks to a change in the interconnection given that hardware designers are using alternatives such as NVLink and InfinityFabric, which do not improve bandwidth but do reduce the latency.
Lane management is a new feature that allows hardware to maintain uniform physical signal clarity in lanes when multiple PCIe devices are connected to the same controller. This is particularly important when using multiple critical devices, such as RAID SSDs or HPC accelerators that require uniform performance between all of them. In other words, if we have two SSDs connected, both will receive the same bandwidth, never one will prevail over the other.
Finally, new I / O virtualization features (input / output, input / output) are added that are oriented to cloud computing environments. They have not given too much information about this feature at the moment.
And now, towards the PCI-Express 5.0
Once the final specification 1.0 of PCI-Express 4.0 has been published, PCI SIG already has its sights set on the next version, PCI-Express 5.0, which according to the agenda will arrive by mid 2019. At the moment, it is unknown what will it bring, although it is easy to imagine that they will work on at least providing twice the bandwidth of generation 4.0 among other things.