Asetek is the world’s leading supplier of liquid cooling systems for computers with over 1.5 million cooling systems shipped for workstations, desktop PCs and servers. Asetek RackCDU™ Direct-to-Chip hot water cooling system leverages Asetek’s proven technology and at scale liquid cooling manufacturing capabilities to produce systems that deliver energy savings of up to 80% and server rack density increases of up to 2.5x-5x times compared to air-cooled data centers, with rapid ROI and low TCO.
RackCDU is deployed at a rack/server level providing maximum scalability. The system consists of a zero-U rack level Cooling Distribution Unit (hence RackCDU) and direct-to-chip server coolers for each server. The RackCDU is mounted in a 10.5-inch (263mm) rack extension that is equipped with monitoring system that includes sensors, alarms and software.
Server cooling liquid moves between RackCDU and server coolers via tubes that attach to both with dripless quick connectors. The server cooler connecting tubes and RackCDU are delivered pre-filled with coolant. Data center operators never have to deal with server cooling liquid.
Asetek RackCDU uses a distributed pumping model. In the distributed model the RackCDU is a passive device (there are no pumps in RackCDUs) and the server coolers provide the circulation pumps. Each server cooler places an integrated pump / cold plate unit on the CPUs and/or GPU in the server. These pump / cold plate units are drop-in replacements for the air heat sinks normally placed on CPUs and GPUs. The pump / cooled plate units are connected in series and each has sufficient pumping power to cool the whole server, providing redundancy.
This model makes each server self-provisioning with respect to liquid cooling flow and makes the pressure needed to operate the system very low. For the data center operator having self-provisioning servers means that no adjustments need to be made to the system when servers are added to or removed from a rack.
Centralized pumping systems require high pressure to provide flow to many servers from a central point. High pressure increases stress within the system and stress leads to failures. The benefit of a low pressure distributed model is a more robust cooling solution and, in the unlikely event of a failure, a blast radius that is limited to a single rack.
RackCDU Direct-to-Chip server coolers are drop in replacements for the existing air heat sinks. RackCDU is deployable with as as part of completely new clusters, in server refresh cycles or even as retrofits of existing servers. When retrofitting existing servers, liquid tubes generally enter and exit through an unused PCIe slot.
The first new production supercomputer to incorporate this technology is Cray’s CS300-LC. The first deployment of RackCDU is in a retrofit of the Skynet Cluster at the National Renewable Energy Laboratory (NREL) in their liquid cooled ESIF data center. This retrofit was completed and turned over for user operation in June 2013.
Bringing liquid cooling directly to the heat source as done by Direct-to-Chip provides for dramatic reductions in cooling energy and fan energy saving in the IT power load, while enabling server densities beyond what is achievable with air cooling and providing for the ability to enable waste heat recycling.
To learn more, contact Asetek today.