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Final PCIe 6.0 specs unleashed: 64 GTps link speed incoming... with products to follow in 2023

Jones in the Fast Lane with switch to PAM4

The completed PCIe 6.0 specifications have finally been unleashed by the PCI-SIG consortium, effectively doubling the speed of the PCIe standard by supporting 64 gigatransfers per second (GTps) with 16 lanes running at 256 GBps.

Announcing the release, the PCI-SIG said that PCIe 6.0 would deliver record performance to power big data applications by doubling the bandwidth and power efficiency of the PCIe 5.0 specification while also providing low latency and reduced bandwidth overhead.

Eager users won't be able to get their hands on PCIe 6.0 hardware for some time, however, as it typically takes 12-18 months after the release of the finalised specifications for products to come to market. This can be seen in the fact that PCIe 5.0 specs were let loose in 2019, while products only really started to trickle out last year.

The PCIe 6.0 specifications are available here.

PCIe has been around for nearly 20 years now as the standard connect for hardware such as network adapters, GPUs and high-speed storage across systems from consumer PCs up to data centre servers. It has been kept relevant by the ability of engineers to double its bandwidth every generation while maintaining full backwards-compatibility.

"PCIe 6.0 technology is the cost-effective and scalable interconnect solution that will continue to impact data-intensive markets like data center, artificial intelligence/machine learning, HPC, automotive, IoT, and military/aerospace, while also protecting industry investments by maintaining backwards compatibility with all previous generations of PCIe technology," said PCI-SIG chairperson and president Al Yanes.

Having said that, the PCI-SIG also states that the PCIe 6.0 specification "requires significant improvements to the package, connectors, and the materials, as we have done with prior speed increases." One of the changes is a switch to PAM4 (Pulse Amplitude Modulation, 4 levels) encoding in order to achieve similar channel reach (physical distance) as the PCIe 5.0 specification.

More details on the technical challenges engineers had to overcome in delivering the increased performance of PCIe 6.0 are available in a PCI-SIG blog post.

When products do become available, PCIe 6.0 technology is likely to show the most benefit in demanding data-intensive applications such as high performance computing (HPC) and AI/ML, by enabling higher bandwidth for kit including GPUs and NVMe SSDs.

But this will take time, as much of the industry has only just broadly adopted PCIe 4.0 across product lines. Intel has only just implemented PCIe 5.0 support in newer processors, and AMD has yet to ship products supporting it, for example.

This has not stopped some analysts from predicting that PCIe 6.0 will begin to see traction, now that the final specifications have been made available.

"With the storage industry transitioning to PCIe 4.0 technology and on the cusp of introducing PCIe 5.0 technology, companies will begin adopting PCIe 6.0 technology in their roadmaps to future-proof their products and take advantage of the high bandwidth and low latency that PCI Express technology offers," said Greg Wong, founder and principal analyst at Forward Insights.

Intel and AMD's next generation of server CPUs, Sapphire Rapids and Genoa, use the CXL interconnect – Compute Express Link – which at that stage will still be based on PCIe 5.0. However, PCIe 6.0 features on Chipzilla's CXL roadmap – as noted by our sister site The Next Platform, so it's only a matter of time. ®

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