PCI Express 7.0 Specs Finalized With An Optical Twist As PCI-SIG Sets Sights On PCIe 8.0
Much like the previous-gen interface, PCIe 7.0 uses PAM-4 encoding (pulse amplitude modulation) signals, with flit-based encoding. Besides the doubling in bandwidth over PCIe 6.0, the new spec should offer better power efficiency, and predictably maintains backwards compatibility with all existing generations. As if that wasn't enough, the SIG says that it's already working on the specification for PCIe 8.0, likely propelled by the AI craze and its computing needs.
Along with the main speed boost, the PCI-SIG also presented the world with the first spec to standardize PCIe connectivity over fiber-optic cables, using a retimer-based solution. That means that theoretically, at some point it'll be possible for you to have your PC in your room and the graphics card a block away.
Besides the ability to use longer cable runs, the optical connectivity spec covers network-like switching capabilities and allows for combining optical- and copper-based PCIe. The icing on the cake is that physical implementations can be made much smaller, too.
All these abilities are particularly handy for datacenters by allowing for far longer cable runs -- and probably much thinner cabling and better power consumption, if we had to guess. The PCI-SIG points out as much, as the spec looks to be just what the doctor ordered for AI/ML and cloud datacenters, environments that value interconnectivity between computing nodes as much as they do raw horsepower.
The PCI-SIG lists AI/ML datacenters, quantum computing, and 800G Ethernet as ideal use cases for PCIe 7.0 and its optical-jutsu. In its PR, the SIG quotes Dr. Ian Cutress from More Than Moore, who states that PCIe 7.0 has generated "more enthusiasm than any previous version." If we had to guess, this is once again due to the fact that large datacenter workloads will take any drop of interconnectivity bandwidth they can get their hands on.
