Liquid Cooling DAC vs. Liquid Cooling AOC: Applications for AI Data Centers

1. Why Are AI Data Centers Moving Toward Liquid Cooling?

As AI foundation models continue to grow in complexity, GPU clusters have expanded from thousands to tens or even hundreds of thousands of GPUs. At the same time, rack power density has increased dramatically, making traditional air cooling insufficient for modern AI infrastructure.

To address these thermal challenges, more AI data centers are adopting advanced liquid cooling technologies, including:

• Cold Plate Cooling

• Immersion Cooling

• Rack-Level Liquid Cooling

Liquid cooling significantly improves heat dissipation while reducing Power Usage Effectiveness (PUE), making it a key technology for next-generation green data centers.

As computing infrastructure evolves, high-speed interconnect solutions must also operate reliably in liquid-cooled environments. Consequently, Liquid Cooling DAC (Direct Attach Copper Cable) and Liquid Cooling AOC (Active Optical Cable) have become essential networking components for AI clusters and high-performance computing (HPC) systems.

2. What Is a Liquid Cooling DAC?

A Liquid Cooling DAC (Direct Attach Copper Cable) is an optimized version of a conventional DAC cable specifically designed for liquid-cooled environments in AI data centers.

Liquid Immersion Transceiver for AI Data Centers | 400G/800G/1.6T Optical Solutions丨C-LIGHT

Compared with standard DAC cables, Liquid Cooling DACs feature enhanced mechanical durability and environmental protection, including:

• Liquid-resistant material construction

• High-sealing connector design

• Corrosion-resistant cable jacket

• High-reliability internal soldering technology

• Long-term operation in high-temperature, high-humidity, and liquid cooling environments

Typical connector options include:

• QSFP56

• QSFP-DD

• OSFP

• OSFP-XD

Supported data rates include:

• 100G

• 200G

• 400G

• 800G

3. What Is a Liquid Cooling AOC?

A Liquid Cooling AOC (Active Optical Cable) is a high-speed optical interconnect specifically engineered for liquid-cooled AI infrastructures.

Liquid Immersion Transceiver for AI Data Centers | 400G/800G/1.6T Optical Solutions丨C-LIGHT

Unlike DAC cables that transmit electrical signals over copper, AOCs utilize optical fiber transmission, providing several advantages:

• Longer transmission distance

• Lightweight cable design

• Excellent electromagnetic interference (EMI) immunity

• Lower signal attenuation

• Higher bandwidth scalability

Liquid Cooling AOCs also incorporate liquid-resistant materials and sealed connector structures, making them compatible with both cold plate and immersion cooling systems.

4. Liquid Cooling DAC vs. Liquid Cooling AOC

5. Advantages of Liquid Cooling DAC

For short-distance connections inside GPU server racks, Liquid Cooling DAC offers several significant benefits:

• Lower deployment cost

• No optical-to-electrical conversion

• Extremely low power consumption

• Ultra-low latency for AI training workloads

• Easy installation and maintenance

• Ideal for Top-of-Rack (ToR) switch connectivity

Typical applications include:

• GPU Server ↔ GPU Server

• GPU ↔ Leaf Switch

• ToR Switch ↔ AI Server

6. Advantages of Liquid Cooling AOC

As AI clusters continue to expand, inter-rack connectivity becomes increasingly important. Liquid Cooling AOC is the preferred solution for medium- and long-distance networking.

Key advantages include:

• Longer transmission distances

• Lightweight fiber cables

• Reduced cable management complexity

• Higher bandwidth scalability

• Better support for high-density cabling

• Lower signal loss

Typical applications include:

• Rack ↔ Rack

• Spine ↔ Leaf

• AI Fabric

• GPU POD

• HPC Networks

7. How to Choose Between Liquid Cooling DAC and Liquid Cooling AOC

General recommendations:

• For connections within 3 meters, choose Liquid Cooling DAC to achieve the best balance of performance and cost.

• For distances exceeding 3–5 meters, Liquid Cooling AOC is recommended to ensure signal integrity and flexible cable management.

8. C-LIGHT Liquid Cooling High-Speed Interconnect Solutions

To meet the networking requirements of liquid-cooled AI data centers, C-LIGHT provides a comprehensive portfolio of liquid cooling interconnect products.

Liquid Cooling DAC Products

• 100G QSFP28 DAC

• 200G QSFP56 DAC

• 400G QSFP-DD DAC

• 800G OSFP DAC

• 800G QSFP-DD DAC

• Passive DAC

• Active Copper Cable (ACC)

Liquid Cooling AOC Products

• 100G AOC

• 200G AOC

• 400G AOC

• 800G AOC

• OSFP AOC

• QSFP-DD AOC

• Custom-Length AOC

Product Advantages

• Liquid-resistant material design

• High-reliability sealed connectors

• Excellent corrosion resistance

• Compatible with cold plate and immersion cooling systems

• Low power consumption

• Ultra-low latency

• High bandwidth

• Compatible with mainstream AI networking platforms

• 100% factory-tested for reliability and stability

9. Future Trends

Driven by the rapid growth of AI foundation models, GPU clusters, and liquid-cooled data centers, 800G and 1.6T networking technologies are becoming the new industry standard.

Future Liquid Cooling DAC and Liquid Cooling AOC products will continue evolving toward:

• Higher transmission speeds (800G, 1.6T, and 3.2T)

• Lower power consumption

• Improved temperature and corrosion resistance

• Lighter cable construction

• Higher-density connector designs

• More comprehensive liquid cooling compatibility certifications

Liquid-cooled high-speed interconnects will play a critical role in the next generation of AI data center infrastructure.

10、Conclusion

Liquid Cooling DAC and Liquid Cooling AOC are both essential interconnect solutions for liquid-cooled AI data centers. Liquid Cooling DAC is ideal for short-distance, in-rack connectivity, delivering lower cost, lower power consumption, and ultra-low latency. In contrast, Liquid Cooling AOC is better suited for inter-rack and medium-to-long-distance applications, offering superior transmission distance, cable flexibility, and EMI immunity.

By selecting the appropriate solution based on network architecture and deployment requirements, organizations can improve network performance, reduce operational costs, and build a scalable infrastructure ready for future 800G, 1.6T, and next-generation AI networking.