Ever since the move away from the AGP interface, PCI Express has become the dominant interconnect standard. Powering everything from graphics cards to storage devices, each generation of PCIe has nearly doubled the bandwidth. The next iteration, PCIe 4.0 has been worked on for a while and the latest roadmaps points to a release next year. Right now revision 0.7 is just about complete but a revision 0.9 is expected before the 1.0 release.
As expected, PCIe 4.0 will allow double the bandwidth per land, allowing for up to 16 GT/s. This increase in bandwidth likely won’t bring massive improvements in graphics cards performance as even the old PCIe 1.1 barely hinders performance. We could see SLI finally go bridge-less like Crossfire has. The bigger benefit will be to storage devices, allowing them to hit more bandwidth for the same number of lanes or reduce the number of lanes and cost but keep the same bandwidth.
The big change though is the new power standard. Right now, PCIe is limited to 75W of power over the slot, meaning higher end cards require additional power connectors. With 4.0, the goal is for 300W to be supplied over the slot. This will eliminate the use of power connectors for all but the most demanding cards, reducing cable clutter. Of course, this means beefing up the motherboard power supply which might make things a bit complicated.
Lastly, we have OCuLink which will bring PCIe to external devices. Hopefully, we’ll get more information about this later but it may become a Thunderbolt and USB Type-C competitor. Don’t expect any of these to arrive very soon though as the standard won’t be finalized until next year. This means Vega and Volta will likely miss it. PCIe 4.0 also won;t be backwards compatible anymore so it will be interesting to see how it all plays out in the end.
