The PCI-SIG (PCI Special Interest Group) which is responsible for maintaining PCIe standard announced that PCIe 4.0 interface shall be showcased in 2016 and be finalized by 2017. The upcoming standard will be using a newer interface method and will be the last copper-based interface for PCI Express. While it’s said that existing cards can work with PCIe 4.0, PCIe 4.0 based add-on cards will not work with PCIe 3.0 slots.
The upcoming spec would provide data rate up to 16 GT/s per lane though the standards are not finalized so the numbers might change by the time an end produce comes out. The PCI-SIG has a long way to go since it also needs to finalize on the length of PCIe 4.0 much needed usually for servers.
Al Yanes, the president of PCI-SIG said,”The base distance is still being validated but it’s typically 7 inches or so. Longer channels of 15 inches or so with two connectors will have retimers, but Gen 3 has used retimers – now we will need to use them for shorter long channels.”
The reason why the PCI-SIG is sticking with a copper-based interface is because they are still working to find a way to make optical connections cost effective for manufacturers to implement with ease. Though they have not started working on it, they’re hopeful that alternatives may crop up before the distant future PCIe standard time frame comes up.
Meanwhile, it will soon release Oculink 1.0 cable, an interconnect which will use four lanes of PCIe 3.0 that provides 8GT/s data rate per lane. One of the useful applications for this is for allowing to provide enough transfer rate for external graphics card options to connect laptops. It is also assumed that this would be a better implementation over thunderbolt interconnect.
Once it arrives, we should see notebooks and other devices taking advantage of a newer interconnect standard, but it would need to compete with the existing USB standard.