We’ve recently explored the societal level trade-offs involved in building data centres to run Artificial Intelligence (AI) workloads. A big part of that discussion related to the power required to run these giant rack farms of computers. The topic was explored in an IEEE article on the use of direct current (DC) in data centres, and robustly discussed on Hacker News.
An enterprise with reasons not to run its workloads in the cloud will often buy a rackable computer that can optionally run on DC, expecting to use dual-redundant alternating current (AC) switching power supplies. This configuration, when combined with an Uninterruptible Power Supply (UPS), allows for higher availability services by protecting against many causes of power failure.
It’s possible to wire the host directly into a DC power source. This is uncommon outside of telco and remote/rural connectivity use cases (like my tri-power camping fridge, which can run off bottled gas, 240V AC or 12V DC).
APNIC has a back office server room, and we don’t use DC power. We have a large UPS, and dual-redundant power on many units. Some of our server infrastructure is co-located in larger data centres in Brisbane and Singapore, and some is in the cloud.
In the Brisbane data centre, we have to monitor a power budget and pay extra when we use more than our budget. Wiring these server farms up is a nontrivial exercise with real-world costs.
Digital logic running on chips uses DC power, which must be converted from AC anyway, usually by a switched-mode Power Supply Unit (PSU) built into the computer. The required DC voltage and current may vary depending on the component, and a PSU can provide 3.5, 5, 12, and 24V DC. This conversion is not ‘free’ — any time power is converted between voltages, or AC and DC, noise, loss, and heat are introduced.
These conversion costs are motivating the exploration of DC power in data centres. If you have enough machines and can concentrate those using DC as the main power source, you can save as much as 10 to 15% of your total power budget. Instead of converting from AC at the back of every device in the rack, you can use a much larger switching unit to provide DC at the rack — and even row — level, and achieve economies of scale.
Direct DC systems can save power, but they typically require costlier cabling to support the load. You’d also need to invest in understanding the risks of managing a DC-powered system (or as one Hacker News commenter put it, “Data center workers are gonna need those big yoink sticks and those thick arc-fault bibs that furnace operators wear“). Those investments may be worth making to save 15% of your energy budget.
Data centre construction was an important topic of discussion at APRICOT 2025 in Bankok, featuring in the ‘Staying ahead with Artificial Intelligence data centres’ panel discussion, and in CSF Advisers Chairman Billy Lee Kok Chi’s presentation on ‘Designing AI-optimized data centres — trends, myths, and sustainability challenges‘.
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