Has the GB200 abandoned optical modules

The GB200 has not abandoned optical modules; it currently uses OSFP optical modules for NVLink expansion, though future designs are moving toward Co-Packaged Optics (CPO).

Current Use of Optical Modules

The NVIDIA GB200 NVL72 systems employ OSFP optical modules as expansion interfaces. Each OSFP module supports 16 differential signal lines, enabling 4 NVLink ports per module. A single NVLink switch in the GB200 contains 32 OSFP connectors, cumulatively supporting 128 NVLink 4 ports . These optical modules are integral to the system's high-bandwidth interconnect, allowing each GPU pair to achieve the 1.8 Tbps aggregate bandwidth required by NVLink 5.0 . The external interconnect of the NVL72 rack, however, uses direct copper backplane connections for intra-rack communication, while optical modules are primarily used for expansion and scaling .

Transition Toward Co-Packaged Optics (CPO)

While OSFP modules remain standard in current GB200 deployments, NVIDIA is exploring CPO technology to address thermal and power challenges in large-scale deployments. CPO integrates optical engines directly with the switch ASIC, reducing power consumption and improving signal density. Mass production of CPO-based switches is expected to support up to 115.2 Tbps signal transmission, with trial production already underway . This indicates a gradual shift toward CPO for future GB200 systems, but optical modules have not been fully abandoned.

Rationale

The continued use of OSFP optical modules is driven by:

• Bandwidth requirements: 800G modules cannot meet the 1.8 Tbps per GPU pair needed for Blackwell GPUs, necessitating 1.6T optical transceivers .
• System compatibility: Current GB200 racks ship with 1.6T optical ports, and adapters for older 800G modules introduce unacceptable latency .
• Scalability: Optical modules allow flexible expansion of NVLink ports across multiple racks without redesigning the copper backplane .

Conclusion

In summary, GB200 systems continue to use OSFP optical modules for NVLink expansion, particularly for high-bandwidth interconnects. The industry is moving toward CPO solutions to improve efficiency and thermal performance, but this represents a future evolution rather than a complete abandonment of optical modules .