Water-cooled server racks remain a rare thing in data centres. But IBM's move to offer an add-on water-cooling unit for its Intel-based xSeries servers and other systems should increase the technology's visibility as a potential solution to heat problems.

IBM used water cooling in its mainframes for a long time but gave up on the technology as it shifted to smaller and less-expensive versions of those systems a decade ago. Now, the increasing density of blade servers is giving water cooling new life.

IBM's eServer Rear Door Heat eXchanger, code-named Cool Blue, is designed to handle the heat produced by large racks of blades and other high-density systems. It can be retrofitted on the company's standard 42U enterprise rack, which houses xSeries servers, and it's also available as part of IBM's Linux-based Cluster 1350 system.

Heat eXchanger uses chilled water from existing air-conditioning systems in data centres. IBM claims the eXchanger will reduce server heat emissions by about half and lower energy costs by 15 per cent.

Pund-IT Research analyst, Charles King, said that because of the heat generated by newer processors, many IT managers are suddenly looking at power and heating and air-conditioning requirements that are going off the scale. IBM's offering could help users buy some time before they have to rebuild or retrofit their data centres, King added.

Vendors such as Knurr and American Power Conversion already offer water-cooled units for servers. But Illuminata analyst, Gordon Haff, said IBM will bring credence to the technology because of its prior experience with mainframes.

Lucas Mearian contributed to this story.