Power sipping bandwidth bottleneck busters – or that's the hope, anyway
GTC Nvidia is set to make available Ethernet and InfiniBand switches featuring silicon photonics with co-packaged optics to advance its vision of datacenters with "millions of GPUs," arguing that the equipment can keep power consumption down.
The GPU-accelerated computing biz unveiled new Spectrum-X and Quantum-X switches at its GTC shindig in San Jose, California, today, claiming these will enable "AI factories" with millions of GPUs connected on-site, while drastically reducing energy consumption and operational costs for operators.
A key part of this comes from co-packaged optics – the integration of the optical and silicon components onto a single packaged substrate. In network switches, this typically means doing away with pluggable transceiver modules that house the optics and digital signal processor (DSP), and integrating these alongside the switch ASIC instead.
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Benefits of CPO are understood to be greatly reduced power consumption, higher bandwidth and lower latency, mainly because of fewer DSPs and the removal of lengthy copper circuitry tracks.
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Omdia datacenter computing and networking expert Manoj Sukumaran was enthusiastic about the move, describing it as a "real big deal." He told us that co packaging optics is a technology which has been "in the works for a long time now. The technology, vendors and standards were fragmented across various small players and their custom solutions.
"There was no standardization for this technology and because of it there was no wide adoption of it even among hyperscale CSPs.
"Now with Nvidia launching CPO, all this will change in a big way," he opined. Sukumaran said the energy cost of networking was always a big concern and for companies like Meta, Omdia estimated it was "at around 30 percent of their datacenter energy bill, primarily consumed by the millions of pluggable optical modules deployed." He said CPO is thus "indeed a compelling technology solution.
"When it comes to the timing, I believe 2026 would be the year of CPO switching going mainstream."
Andy Buss, Senior Research Director, IDC EMEA, told The Reg the silicon photonics switches had "the potential to drastically decrease power consumption within datacenters and large AI clusters and solutions."
Buss added: "Even today, 10G Ethernet still has a high per port power draw for copper RJ45 connections, and when we go to current optical transceivers and pluggable modules at high data rates, the power consumption per module is noticeable – and with the number of network connections required can quickly ramp up to be a significant consumer of power. This can be in the region of 20W to 40W per transceiver, so this is not insignificant – and this also needs to be not only powered but cooled as well.
"With the uplift in connectivity with AI, this will only get worse over time, so a new solution is needed. Intel and others have long talked about integrating silicon photonics into CPU packages, but this has not translated from packaging concept to production products, so for NVIDIA to announce this and for availability in the near future is a big deal."
Last year, optical networking specialist Ayar Labs told The Register it believed that integrated optics were be the only way forward to address the bandwidth bottlenecks in scaling beyond a single rack of GPU servers to support ever larger AI models.
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The Quantum-X Photonics InfiniBand products are set to be available later this year. These will provide 144 ports of 800 Gbps InfiniBand based on 200 Gbps SerDes and feature a liquid-cooled design to take the heat away from the onboard silicon photonics.
These switches will offer double the speed and 5x greater scalability for AI compute fabrics compared with the previous generation, Nvidia claims.
Meanwhile, the Spectrum-X Photonics Ethernet products are coming in 2026 and will offer multiple configurations. These include 128 ports of 800 Gbps or 512 ports of 200 Gbps, delivering 100 Tbps total bandwidth, plus 512 ports of 800 Gbps or 2,048 ports of 200 Gbps, for a total throughput of 400 Tbps.
From what Nvidia has disclosed, its silicon photonic capabilities have been developed in partnership with a number of other firms, most notably Taiwanese semiconductor giant TSMC.
Nvidia even included a statement from TSMC chairman and CEO C.C. Wei, who enthused that: "TSMC's silicon photonics solution combines our strengths in both cutting-edge chip manufacturing and TSMC-SoIC 3D chip stacking to help Nvidia unlock an AI factory's ability to scale to a million GPUs and beyond, pushing the boundaries of AI."
Along with sovereign AI, "AI factories" is a favorite talking point of Nvidia chief Jensen Huang, who coined the term to refer to datacenters specially built to handle the most computationally intensive AI processing tasks, such as xAI's Colossus. Expect to hear more on those themes during GTC.
"AI factories are a new class of datacenter with extreme scale, and networking infrastructure must be reinvented to keep pace," Huang said.
"By integrating silicon photonics directly into switches, Nvidia is shattering the old limitations of hyperscale and enterprise networks and opening the gate to million-GPU AI factories."
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Nvidia is not the only firm unveiling network switches with co-packaged optics. Micas Networks announced this week its 51.2T product offering 128 ports of 400G Ethernet, based on Broadcom's 51.2 Tbps Bailly CPO switch platform.
This features the latter's Tomahawk 5 switch chip directly coupled to and co-packaged with 8 x 6.4 Tbps silicon photonics chiplets-in-package (SCIP) optical engines. Micas said it is accepting orders now, and fulfilling on a first-come-first-served basis. ®