Nvidia’s new silicon photonics-based 400 Tb/s switch platforms enable clusters with millions of GPUs

At GTC 2025, Nvidia introduced its Spectrum-X Photonics and Quantum-X Photonics networking switch platforms for exascale datacenters that use silicon photonics. The new networking switch platforms up data transfer speed to 1.6 Tb/s per port, and 400 Tb/s in the aggregate, allowing millions of GPUs to operate together seamlessly. Nvidia says the new switches offer higher bandwidth, lower power loss, and superior reliability compared to conventional networking solutions. 

The Spectrum-X Photonics Ethernet and Quantum-X Photonics InfiniBand platforms deliver speeds of 1.6 Tb/s per port (twice the maximum of current top-tier copper Ethernet solutions) and total bandwidths reaching 400 Tb/s through various port configurations. Nvidia’s Spectrum-X Photonics switches come in several configurations, offering 128 ports at 800 Gb/s or 512 ports at 200 Gb/s, reaching a total bandwidth of 100 Tb/s. A higher-capacity model provides 512 ports at 800 Gb/s or 2,048 ports at 200 Gb/s, achieving 400 Tb/s throughput. The Quantum-X Photonics series features 144 ports at 800 Gb/s InfiniBand, using 200 Gb/s SerDes for efficient data transmission. 

Compared to previous-generation networking solutions, Quantum-X doubles performance and increases AI compute scalability fivefold, making it suitable for high-intensity workloads and building even bigger AI clusters. 

The Quantum-X InfiniBand switches include a liquid cooling system, ensuring the onboard silicon photonics chips operate at peak efficiency without overheating. As a result, the new networking platforms promise 3.5 times better energy efficiency, 10 times greater network reliability, and 63 times stronger signal integrity, reducing power consumption and improving long-term performance. Additionally, deployment speeds increase by 1.3 times, making these switches a more effective solution for hyperscale AI data centers, according to Nvidia. 

Nvidia’s Spectrum-X Photonics Ethernet and Quantum-X Photonics InfiniBand platforms use TSMC’s silicon photonics platform called Compact Universal Photonic Engine (COUPE) that combines a 65nm electronic integrated circuit (EIC) with a photonic integrated circuit (PIC) using the company's SoIC-X packaging technology. Nvidia also worked with Coherent, Corning, Foxconn, Lumentum, Senko, and others to establish its own silicon photonics ecosystem with a steady supply chain that enables Nvidia and its partners to build AI clusters and data centers that were impossible before using proprietary hardware. 

Nvidia expects Quantum-X InfiniBand switches to be released later in 2025, while Spectrum-X Photonics Ethernet switches will arrive in 2026. 

While these advancements promise significant improvements, integrating silicon photonics at such a large scale is complex, and widespread adoption depends on organizations being willing to upgrade their existing networking infrastructure. Despite these hurdles, Nvidia’s silicon photonics technology is a major step forward in AI networking. While Nvidia yet has to disclose future plans for its networking gear, TSMC’s COUPE has a very promising roadmap, which will perhaps be followed by Nvidia. 

TSMC's next iteration of silicon photonics will incorporate COUPE technology within CoWoS packaging, combining optics directly with a switch. This will allow optical connections at speeds reaching 6.4 Tb/s. The third version aims to push speeds to 12.8 Tb/s, integrating directly into the processor package.