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Monday - August 8, 2022

Server Cooling: Balancing Efficiency and Performance

Data. One of the most valuable things on the planet right now. From data collection, processing, and distribution – our increasingly digital world explains the growing need for efficient data storage solutions. The largest data center in the U.S. is over 7 million square feet and they continue to grow in size and server density. Higher server density requires more efficient and effective cooling to keep equipment running and data flowing.

According to Omdia, server shipments are expected to increase 8% year over year to an estimated 20 million by 2025. Most of this growth is driven by two segments: open compute servers (OCP) and Hyper-converged infrastructure (HCI). OCP servers are a standardized design that is meant for modular, plug-and-play data center configurations. While HCI is less flexible, it is more advantageous for small, remote organizations and provides a simple, combined hardware solution.

Efficient Server Cooling for the Rapidly Growing OCP Market

Large data centers consume a TON of energy – sometimes as much as it takes to power a small city. Environmental activists are aware of the energy toll caused by digital corporations and are increasing pressure to implement efficient technology using renewable resources.

Cooling is one of the biggest power draws because server equipment produces a lot of heat during operation. It is critical to maintain the optimal operating temperature range within data centers because when temperatures exceed the recommended maximum, equipment could fail and cause data blackouts. In fact, many attempts to increase power density when designing data centers or server cabinets are limited by the available cooling capacity. Data center operators are constantly navigating new hurdles in their quest for maximum efficiency.

Liquid Cooling Technology Improves Server Cooling Capacity

New thermal management trends for data centers include innovative liquid cooling technology that promises to help increase energy efficiency. Because water has a significantly higher heat capacity than air, it is the preferred cooling solution for high density systems.

The most advanced type of liquid cooling solution – immersion cooling – involves immersing server hardware into an electronic-safe liquid. During single phase immersion cooling, electronics are sealed and then immersed in liquid which is then pumped across a heat exchanger. The single-phase form of immersion cooling allows components to be more assessable, however it is not as effective as two-phase.

During two-phase immersion cooling, the electronics are immersed directly into a liquid with a low boiling point. One the liquid boils, it turns to vapor which is then condensed across a heat exchanger and returns to it’s cooled state. This method is highly effective and enables the highest possible power densities.

Economies of Scale Drive Server Cooling Solutions

Integrating liquid cooling typically requires a large initial investment which has, so far, limited widespread adoption. Cooling fan manufacturers are developing high performance fans to fill this gap in the market – more efficient heat sink designs and cooling plates can be used to maximize heat dissipation. Research recently published in Science Daily describes new copper conformal coating technology that can transform a traditional bulky heat sink into a compact “heat spreader”.

Another option is cold plate cooling – also known as “direct-to-chip” – that uses a combination of air and liquid cooling. A liquid-cooled metal plate is attached to the top of a CPU/GPU where it then absorbs any generated heat. The heated liquid is circulated into a chiller or cooling tower and then routed back to the plate to repeat the process. Since the liquid is only cooling the CPU/GPU in this process, air cooling is used to dissipate the remaining heat.

Counter Rotating Technology Improves Fan Reliability

Advanced fan technology can help improve the reliability of air cooling solutions. Counter-rotating fan technology consists of inlet and outlet fans that rotate in opposite directions. By rotating in the opposite direction, the second fan counteracts the wide air flow that is produced by the first fan. In this manner, the air is directed into a straight, concentrated flow with significantly higher static pressure than is possible with two fans rotating in the same direction.

Adding PWM control to these fans further improves their efficiency as the speed is regulated by the component temperature. When the temperature rises above a defined threshold, the input signal is activated and the fan speed increases. These sequences are called duty cycles and by varying these with PWM control, users can reduce the noise and power consumption of their system.

Innovation is Powered by Data

The need for data will continue to grow – from AI engines to autonomous vehicles – vast amounts of data will need to be processed in our near future. Reliable cooling solutions will need to meet the extreme performance demands and volume requirements of data center operators. NMB offers a broad range of high performance and efficient DC axial single rotor and counter-rotating fans with PWM control and NMB ball bearings. Learn more about how we can support your server and data center cooling needs.

Fernando Palarca
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