THE CRUNCH
NVIDIA has introduced the MMS1X00-N5400, a QSFP112 form factor optical transceiver designed for high-speed networking in AI environments. The module uses 1310nm lasers to deliver 400Gbps over single-mode fibre and features an MPO-12 connector. It includes external heatsinks to aid thermal management in hot datacentre aisles.
The device uses 112G PAM4 signalling across four channels, which allows it to achieve 400Gbps without needing a gearbox, unlike the older QSFP56-DD standard. This makes it a drop-in replacement for existing DR4 optics in many setups. The author notes that the modules cost more than direct-attach cables but offer greater flexibility for switching and integration in AI clusters.
The author tested the optics with a ConnectX-8 NIC and an NVIDIA Spectrum-X switch, confirming they autonegotiated to 400Gbps speeds. The modules run at a maximum of 10W and remain cool, even in the warm environment of a liquid-cooled AI station. This reliability is highlighted as a key benefit for large-scale deployments where generic optics might struggle with heat.