In data centers, pluggable optical transceivers convert electronic bits to photons, fling them across the room, and then turn them back to electronic signals, making them a technological linchpin to controlling the blizzard of data used in AI. But the technology consumes quite a bit of power. In a data center containing 400,000 GPUs, Nvidia estimates that optical transceivers burn 40 megawatts. Right now, the only way to deal with all that heat is to hope you can thermally connectthese transceivers to the switch system’s case and cool that. It’s not a great solution, says Thomas Tarter, principal thermal engineer at startup xMEMS Labs, but because these transceivers are about the size of an overlarge USB stick, there’s no way to stick a conventional cooling fan in each.
Now, xMEMS says it has adapted its upcoming ultrasonic microelectromechanical (MEMS) “fan-on-a-chip” to fit inside a pluggable optical transceiver so it drives air through and cools the transceiver’s main digital part, the digital signal processor (DSP). Keeping the DSP cool is critical to its longevity, says Tarter. At upwards of US $2,000 per transceiver, getting an extra year or two from a transceiver is well worth it. Cooling should also improve the integrity of the transceivers’ signals. Unreliable links are blamed for extending already lengthy training runs for new large language models.
xMEMS’ Cooling Tech Finds a New Home
The xMEMS chip-cooling tech, which was unveiled in August 2024, builds on the company’s earlier product, solid-state microspeakers for earbuds. It uses piezoelectric materials that can change shape at ultrasound frequencies to pump 39 cubic centimeters of air per second through a chip just about a millimeter high and less than a centimeter on a side.
Smartphones, which are too slim to carry a fan, were the first obvious application for the MEMScooler, but cooling the fast-growing data-center-scale AI systems seemed out of reach for MEMS technology, because it can’t come near to matching the liquid cooling systems removing thousands of watts of heat from GPU servers.
“We were pleasantly surprised by the approach by data-center customers,” says Mike Housholder, xMEMS vice president of marketing. “We were focused on low power. So we didn’t think we had a slam dunk.”
Pluggable optical transceivers turn out to be a data-center technology that is squarely in the fan-on-a-chip’s wheelhouse. Today, heat from a transceiver’s DSP, photonics IC, and lasers is thermally coupled to the network switch computers they are plugged into. (These usually sit at the top of a rack of computers.) Then air moving over fins built into the switch’s face removes the heat.
In collaboration with partners they would not name, xMEMS began exploring how to get air flowing through the transceiver. These parts consume 18 watts or more. But by situating the company’s MEMS chip within an airflow channel that is thermally connected to the transceiver…
Read full article: xMEMS Ultrasonic Coolers for Power Hungry Transceivers
The post “xMEMS Ultrasonic Coolers for Power Hungry Transceivers” by Samuel K. Moore was published on 05/02/2025 by spectrum.ieee.org