Future Versions of PCIe Express Could Use Optical Technology

Today’s computers lean heavily on the PCI Express bus to make everything work, and it does a great job at catering to our needs for high bandwidth connections between all of our components. However, demands are constantly increasing, and the PCI-SIG group that develops these standards is always looking far over the horizon to stay ahead of the curve. While it’s currently working on technologies like PCIe 6.0 and 7.0, it’s also looking even further into the future with news that it’s convened a workgroup to explore a radical shift to an optical interconnect instead of the electrical one it’s always had.

Currently, we use PCI Express to connect all the essential parts of our PC, including the CPU to the GPU, the SSD to the CPU, and so forth. Though this satisfies our current demands quite nicely, the PCIe bus has some significant drawbacks, including the heat it generates. We’re already starting to see this become a problem with the introduction of PCIe 5.0 SSDs, the first PCIe storage devices that will practically require a heatsink and a fan to keep temperatures in check. This was never an issue with previous iterations of SSDs using both SATA and the PCIe bus, but as bandwidth doubles each generation, heat is starting to become an issue. You can just imagine what it will be like for a Gen 7 SSD in 2027 or so; thus, a new technology will be needed.

Credit: Eric Kilby, CC BY-SA 2.0

According to PCI-SIG, it’s convened a technology-agnostic workgroup to explore delivering PCI Express technology over an optical connection instead of the electrical one we use today. The benefits would be wide-ranging, allowing for improved performance with less heat generated, along with reduced latency while allowing for longer connections simultaneously. Overall it would totally upend the entire PC industry, as switching from electrical connections to optical ones would require every part of a PC to be redesigned from the group up and would mark a tectonic shift within the world of computers.

Unfortunately, though the idea of an optical GPU is exciting, it’ll be many years before it becomes a reality. The working group is now being formed, so it likely won’t be putting pen to paper until 2024. Even if it does develop a draft spec of this future technology, it could be years before it is turned into physical products. As just one example, the current PCIe standard is PCIe 4.0, finalized in 2017, according to HotHardware. That means it took six years to become the norm. These things also tend to get delayed, as we predicted PCIe 6.0 would be coming in 2022, all the way back in 2019! Therefore, if optical interconnects are ratified for PCIe in 2025, we might not see them in the flesh until 2030 or so, if we’re lucky.

Another factor that’s bad news for those of us who just want faster gaming PCs with this technology is that it will likely be deployed for enterprise before it reaches home users. In the press release, PCI-SIG explicitly states businesses such as “Cloud and Quantum Computing, Hyperscale Data Centers and High-Performance Computing will benefit from PCIe architecture leveraging optical connections.”