PCI-SIG Releases PCIe 4.0 Specs

PCI-SIG released the specs for PCIe 4.0, which promises data transfer rates of 16GTps, and said work on PCIe 5.0 is well under way.

PCI-SIG is a 750 member-strong organization that governs the nigh-ubiquitous protocol. It typically releases major updates to PCIe on a four-year cycle, but the last release was PCIe 3.0, which debuted in 2010. That means it took almost twice as long to finalize and release PCIe 4.0 as its predecessors—but don't think that means development is shifting to a seven-year cycle. PCIe 5.0 is expected to make its debut in 2019.

Al Yanes, the chairman and president of PCI-SIG, discussed PCIe 4.0's highlights in a blog post. Yanes said the protocol offers:

  • Extended tags and credits for service devices
  • Reduced system latency
  • Lane margining
  • Superior RAS capabilities
  • Scalability for added lanes and bandwidth
  • Improved I/O virtualization and platform integration

These appear to be significant improvements to PCIe. As we said when we reported on PCIe 4.0 back in August 2016, the protocol isn't just for video cards anymore. Many different components, from storage to networking, are using PCIe to send signals to a CPU. PCIe 4.0 could reduce the price of NVMe SSDs (thanks to needing only half the lanes) and enable 10GbE connections over a single lane, for example.

Not that we'll have to live with PCIe 4.0 for long. PCI-SIG said in June that the spec entered the 0.3 release phase in its development and that it was fast-tracked for an early 2019 debut. The organization also reiterated that timeline at Hot Chips 2017 and predicted that the 0.5 release would be ready for the fourth quarter. It did not, however, reiterate that point in the email it sent announcing PCIe 4.0's release; it merely said the 0.3 release has been released. But it did offer a more specific Q2 2019 timeframe for the targeted release.

Still, it's important to note that PCI-SIG releases the specs, not the products that rely on them. We don't expect Intel to support PCIe 4.0 until mid-2019, and AMD has said it plans to add support in 2020. That means we're unlikely to see any PCIe 5.0 products until 2020-2023, depending on how much the companies stick to these gaps between the specs' release and support for them.

Now that the specification is set, companies can build compliant products. A number of PCIe 4.0-related news also appeared today in the form of protocol analyzers. In the last week, we've had a number of PCIe 4.0 product leaks. An AMD roadmap pins a GPGPU / GPU with the technology in Q4 2018. Several retailers that listed the upcoming Intel Optane SSD 900P early show PCIe 4.0 connectivity (although we think this is in error), and Intel has muttered about PCIe 4.0 a time or two, with upcoming chipsets set for release in 2018.

All signs lead us to believe we will have PCIe 4.0 in the consumer space next year. The technology will enable manufacturers to lower the number of lanes per device to achieve performance levels we have today or to take a leap to new levels by utilizing the same number of lanes we use now. In notebooks, we should see greater battery life and an improved user experience. Desktops will get a hefty performance boost, as well. The technology will move us closer to true photo-realistic gaming that will impact both virtual and augmented reality.

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