The PCI-SIG released the PCIe 7.0 specifications for next-generation interconnects. We had this one on the list for a few days ago, but AMD’s event ended up being too big. As a result, we are playing some Father’s Day catch up (also happy Father’s Day to all the dads of STH!)
PCI-SIG Releases PCIe 7.0 Specifications and Optical PCIe 6.4 and 7.0
The new generation is set to deliver 128.0 GT/s in raw bit rate. That will mean up to 512GB/s of bidirectional bandwidth via a PCIe Gen7 x16 slot. PCIe 7.0 will also utilize PAM4 signaling and flit-based encoding. PAM4 as its 4-levels offers a solid foundation for higher-speed interconnects.
Also announced at the same time is a new PCIe Optical solution. This is being added as a PCIe 6.4 change as well as a PCIe 7.0 feature. The new PCIe Optical Interconnect Solution uses an Optical Aware Retimer as part of an engineering change notice (ECN.)
We have shown some early use cases around this including an optical SSD by Kioxia and Kyocera.
We have another demo that we have not shown off yet that uses optical not just for PCIe but also for CXL memory. Adding an optical interconnect allows for further reach beyond just a chassis or a rack. It also allows for techniques like multiplexing signals over optical fibers. Imagine, for example, having access to pools of NVMe storage, memory, or other devices over high-speed PCIe-based shelves without having to switch to an Ethernet or other protocol. Our sense is that the data centers that are striving for hyper-scale AI will be the first to adopt technology like this as they see to disaggregate non-core AI components out of racks, starting with power supplies, fans, and so forth.
Final Words
While we do not expect to see PCIe Gen7 in next year’s (2026) server products, we fully expect the rate of PCIe generations to continue to increase. The PCI-SIG announced that pathfinding to PCIe Gen8 is already underway.
Also, AMD Infinity Fabric XGMI is coming to PCIe 7; and 7 will improve CXL.
It will be the grand convergence, after which we can have a slight slowdown; which will accommodate that things simply can’t go faster with current technology and motherboard materials.
Moreover, AMD’s Infinity Fabric XGMI is set to arrive with PCIe 7, which will also bring enhancements to CXL.
This marks a major convergence point, after which we might see a modest deceleration — a necessary adjustment, as we’re approaching the physical limits of current technologies and motherboard materials.