PCI SIG has revealed that the PCI Express standard will get another lift before it may be time for a change. The new version will be called PCI Express 4.0 and will offer speeds up to 16 Gbit/s, double up to PCI Express 3.0. After PCI Express 4.0 there is talk about moving on to a new standard since it might be hard to scale the technology further.
PCI SIG has had some difficulties with the latest standard PCI Express 3.0, which is slated to appear next year. It had to redo the signal coding and other properties, while remaing backwards compatible to PCI Express 2.x and 1.x.
With PCI Express 4.0, or Gen 4 as it is currently called, will according to previous reports is doable, but the details need some work. It is doing simulations together with partners like AMD, HP, IBM and Intel and says that the bandwidth at 16 Gbit/s is possible, but the final report is not due until the end of the year.
A limitation that is already known with Gen 4 is that the lanes on the mothebroard and other circuit boards will be limited to a length of only 12″, unlike 20″ with PCI Express 3.0. It will be possible to use longer lanes through ”Repeaters”, but this will increase the final cost and increase the complexity of the circuit board.
PCI Express uses copper and is expected to continue using it with Gen 4, but after that it might be time to consider optics for the successor to the PCI Express standard.