Time marches on, and so does the PCI Express standard. The PCI SIG pre-announced PCI Express 6.0 on Tuesday, scheduled to bring I/O transfer rates of 256 gigabytes per second (GBps) in a few years.
For I/O fans, the PCI Express standard is snarled at the intersection of the past, present and future. Less than a month ago, at Computex in Taipei, AMD announced that the X570 chipset and Ryzen 3800X would be the first to support PCI Express 4.0 and its 64GBps interface. The majority of PCs are stuck on PCI Express 3.0, with data transfers of 32GBps. (Here’s everything you need to know about PCI Express 4.0.)
A few days later, the PCI Express 5.0 specification was published, supporting up to 128GBps. It’s too early to tell when products supporting that specification will arrive, though most likely they’ll arrive in 2020.
The PCI SIG’s pre-announcement of the PCI Express 6.0 standard includes a target date of 2021 for the release of the specification. Actual products based upon that spec would be expected to appear a year or so later.
The PCI SIG is racing along at a pace somewhat akin to Moore’s Law for CPUs. The SIG is concerned with doubling I/O bandwidth every three years, meaning the SIG’s PCI Express standard has to keep up with and even exceed that. It took more than six years between PCI Express 3.0 (2010) and PCI Express 4.0 (late 2017), but the SIG now appears to be back on track.
Technically, PCI Express 6.0 supports a 64 gigatransfer raw rate across a x16 configuration. It utilizes PAM-4 encoding, leveraging the existing 56G PAM-4 already in the industry. It includes low-latency forward error correction, too. More importantly, it’s also backward-compatible with previous PCIe specifications, as the previous specs have been, too.
In all, PCI Express 6.0 isn’t something you’ll need to worry about, or covet, for a few years. But the groundwork is being laid.