H3C's Core Liquid Cooling Breakthrough: Redefining 800G Switch Reliability for AI Clusters

As AI computing scales to tens of thousands of GPUs, the most pressing issue in data centers has shifted from “not computing fast enough” to “not dissipating heat fast enough.” As the core network connecting all computing resources, the cooling capability of switches directly determines the stability and deployment timeline of the entire AI cluster. Traditional air cooling has reached its limit, making liquid cooling the inevitable choice. Today, cutting-edge AI computing platforms such as NVIDIA’s Rubin are establishing “high-temperature” liquid cooling as the cooling standard for next-generation green data centers. This signals that building an end-to-end high-temperature liquid cooling system has become an industry consensus. Yet the real challenge remains: how can liquid cooling be made as reliable as power supply—becoming a default, worry-free configuration for operations teams, rather than an additional “circulatory system” requiring extra maintenance?

The answer is clear: redefine reliability through quantifiable and verifiable engineering practices. Building on its S9827 series 800G switch platform, which already incorporates liquid cooling design and has been validated through large-scale deployments, H3C has refined liquid cooling into a mature and reliable foundational technology through continuous innovation. This is not merely about attaching cold plates to switches but represents a systematic reengineering from components to the entire device. It employs a hybrid air-liquid cooling architecture, achieving precise liquid cooling coverage for core heat sources such as MAC chips and optical modules, while using air cooling as a system-level supplement. Validated by real-world test data, this design provides measurable and trustworthy cooling capabilities for AI clusters scaling to tens of thousands of units.

Fig. 1: H3C S9827 Series Data Center Switch

Adaptive Contact Technology: Tackling the Temperature Uniformity Challenge of High-Power Optical Modules

For operations engineers, the foremost challenge in deploying high-power, high-density liquid-cooled switches is ensuring that core components do not overheat. As high-speed optical modules such as QSFP-DD become increasingly compact in design, their thermal density rises sharply. When 64 such high-heat sources are densely arranged, the first barrier is to efficiently dissipate heat and "keep" the temperature of each port below the safe threshold. Beyond this, an even deeper challenge—one that determines whether the system can be reliably deployed at scale—is how to maintain highly consistent and stable cooling performance across all ports under conditions of long-term operation, repeated plugging and unplugging, and complex assembly tolerances.

To address this challenge, the H3C S9827 series switches introduce the innovative Adaptive Contact liquid cooling architecture. At its core lies the exclusive patented Dual-Floating Hard Tube Technology. This technology employs coordinated micro-movement between cold plates and coolant tubes to actively absorb and compensate for all microscopic deviations in optical modules.

Testing under full-load operational traffic confirms that the temperatures of all optical module housings remain stably within safe thresholds. Moreover, temperatures across all 64 ports remain highly consistent, with variations controllable within 5°C.

The key to this outstanding performance lies in the patented design, which ensures highly uniform contact thermal resistance across all port cold plates. This achieves zero-gap, tight contact and efficient heat dissipation for every port, fundamentally eliminating uneven cooling caused by poor contact.

Fig. 2: Adaptive Contact liquid cooling architecture

This innovation directly addresses the persistent challenges of high contact thermal resistance and uneven heat dissipation caused by tolerances and repeated insertions/extractions. Customers no longer need to worry about poor thermal contact resulting from structural dimensions, assembly tolerances, or frequent plugging and unplugging. More importantly, it ensures that every port achieves consistent cooling performance and controlled temperatures with deterministic reliability—effectively transforming thermal management risks into a trustworthy foundational capability.

Liquid-Electric Physical Isolation: Building the Foundation of Intrinsic Safety for Liquid Cooling

While heat dissipation is addressed, the greater concern lies in safety. For data center managers, the primary apprehension when adopting liquid cooling always centers on "coolant leakage." The traditional safety approach relies on installing leak detection sensors at critical points for post-leak alerts—a fundamentally reactive measure.

The H3C S9827 series switches are dedicated to achieving "intrinsic safety." At its core is the rigorous implementation of the principle of liquid‑electric physical isolation. This is realized through three layers of purely physical safeguards:

First, at the source, the use of integrally‑formed all‑metal hard pipes completely eliminates all aging‑prone sealing rings and weak solder joints, eradicating leakage risks at the root.

Second, at the chassis‑level architecture, strict physical zoning between liquid and electrical pathways ensures that the coolant flow path is physically isolated from critical circuit areas, establishing a clear safety boundary.

Finally, even under extreme scenarios, a precisely Liquid Containment Tray guarantees that any liquid is 100% captured and safely redirected, structurally blocking any possibility of liquid‑electric contact.

Fig. 3: liquid‑electric physical isolation

High-Density Integration: Delivering Dual Returns in Data Center TCO and Energy Efficiency

Traditional thermal management has been a bottleneck for high-density deployment, forcing designs to compromise between size and performance. The liquid cooling technology in the H3C S9827 series switches reverses this logic, transforming it from a limiting factor into a core enabling technology for achieving extreme integration.

The two major innovations discussed earlier culminate in system-level high density and high energy efficiency. The direct outcome is this: the H3C S9827 series stably deploys 64x 800G ports within a compact chassis space, breaking through conventional density limits. This liquid cooling‑enabled high‑density form factor becomes the key lever for unlocking value.

Figure 4: System-Level Outcomes

First, it restructures the cost framework. The exceptionally high port density per device significantly reduces the total number of switches and interconnect cables required to build large‑scale AI computing clusters, lowering procurement costs. At the same time, fewer devices and cables lead to a simpler network topology and fewer potential points of failure, fundamentally reducing the complexity and risk costs associated with long‑term operations.

Second, it redefines green competitiveness—a capability rooted in a system-wide energy efficiency revolution spanning from the device to the data center hall.

At the device level, this efficiency stems from the precise liquid‑cooling design: micro‑channels inside the cold plates direct coolant on‑demand to heat sources such as MAC chips. Real‑world measurements confirm that this design reduces the junction temperature of critical chips by over 10°C compared to air‑cooled configurations with equivalent specifications. Building on this, as liquid cooling assumes the primary heat dissipation load, the fan system can be streamlined—through reduced quantity and lower rotational speeds—ultimately achieving an11% reduction in overall device power consumptionand a23 dB reduction in operational noise.

At the data‑center level, the system’s support for 40°C high‑temperature liquid cooling forms a critical link in the aforementioned end‑to‑end high‑temperature cooling architecture. This enables the switch not only to directly leverage natural cooling sources or waste‑heat recovery, but also to operate in high synergy with server‑side liquid‑cooling systems. In typical deployment scenarios, the efficient heat dissipation dramatically cuts the demand for air conditioning, saving approximately 7,000 kWh per device annually and driving the data center PUE below 1.2.

Ultimately, the value of this enabling technology is redefined: it is no longer a passive thermal‑management expense, but a high‑return investment that leverages savings across procurement, operations, and energy consumption—significantly optimizing the Total Cost of Ownership (TCO) of the data center. Against the backdrop of the“Dual Carbon” strategy, this technology directly lowers PUE and elevates energy efficiency.