SANTA CLARA, Calif. — Google is calling for 48-volt motherboards to cut wasted power in data center servers, a concept Intel already has prototyped seeking industry feedback. The news emerged from representatives of the companies and their power component vendors in a panel at DesignCon here.
Today’s servers generally use 12V power supplies but are stuck at efficiency levels of about 84% as processors drive ever higher power demands. “The short term solution has been to make regulators 101% efficient, but that isn’t going to work anymore,” said Dave Dwelley, a product line manager at Linear Technology.
Dwelley said the industry is coming to the end of an era of discrete voltage regulators. He called for greater integration of the function closer to the points of the power load.
Today’s 12V motherboards have been around for 20 years, said Neil O’Sullivan, a power group manager at Google. Since that time, processors have ratcheted up their power consumption with multicore chips trying to compensate for the end of Denard scaling, he said.
Intel sketched out the pros and cons of a 48V server motherboard design. (Image: Intel)
Telecom systems have been using 48V parts for many years, providing an ecosystem that servers can tap, O’Sullivan said. The smaller connectors can enable denser board designs, albeit they will create challenges for the CPU, he added.
“I can’t emphasize enough that we won’t put voltage regulators close to the processor because they are too noisy – it’s like having a Rottweiler on a chain and you don’t know how long the chain is,” said David Figueroa, director of enterprise power solutions at Intel.
Intel’s current prototype board uses 48V for the main power rails and 12V for secondary ones, seeking feedback from big data center operators such as Google. “We understand the board down to the circuit level, but when it comes to the data center rack we are not the leading experts,” said Figueroa.
Vicor has been selling for a decade a 48V regulator for large graphics chips and DSPs, said Robert Gendon, a vice president at Vicor. Today’s parts use a 3D package suitable for placing near a processor socket, and a future version will use an even denser package that could be placed under the socket, he said.
“Ideally in the future we will place the converter in the CPU package,” Gendon said.
All sides agreed putting voltage regulation into the processor package was a long term goal. But at the 48V level it raises issues with dielectric materials that require new packaging techniques, said Figueroa of Intel.
The panel also agreed it makes sense to support both 48 and 12V rails for a time, given a number of server peripherals operate at 12V optimally today. They debated whether the secondary power level could be scaled to 5V or below for further benefits.
Vicor showed its existing approach to a 48V server motherboard design. (Image: Vicor)
— Rick Merritt, Silicon Valley Bureau Chief, EE Times