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Google Calls For Power Supply Design Changes
Raindance writes "The New York Times reports that Google is calling 'for a shift from multivoltage power supplies to a single 12-volt standard. Although voltage conversion would still take place on the PC motherboard, the simpler design of the new power supply would make it easier to achieve higher overall efficiencies ... The Google white paper argues that the opportunity for power savings is immense — by deploying the new power supplies in 100 million desktop PC's running eight hours a day, it will be possible to save 40 billion kilowatt-hours over three years, or more than $5 billion at California's energy rates.' This may have something to do with the electricity bill for Google's estimated 450,000 servers."
Actually I would bet that Google servers DON'T have a video card, and that all of them have RJ-45 SOL support (or something like it). The reason being that Google has admitted that they fully embrace the commodity distributed server system. Google will periodically host talks at my university where they explain all this in [too much] detail.
:)
Basically, when a machine fails, it is pulled from the rack and replaced with an identical machine with a cookie cutter image. Kinda like the Borg
When a box fails it is probably instantly detected by some machine monitor and taken offline (think: the 'crop' tenders in the Matrix I). The sysadmins arent going to waste time plugging a video cable into the rack... just pull it. Toss the box into a repair queue and let the tech's put a video card into it if needed. Remeber: 100's of machines fail for them every day. That's a fact from the Google talk in 05.
There are 10 types of people in the world. Those who understand binary and those who do not.
Most of the postings so far have it all wrong. Google is not proposing 12VDC into a desktop PC or 12VDC distribution within the data center. What they're proposing is that the only DC voltage distributed around a computer case should be 12VDC. Any other voltages needed would be converted on the board that needed it.
This is called "point of load conversion", and involves small switching regulators near each load. Here's a tutorial on point of load power conversion.
It's been a long time since CPUs ran directly from the +5 supply. There's already point of load conversion on the motherboard near the CPU. Google just wants to make that work off the +12 supply, and get rid of the current +5/-5/+12/-12 output set.
The early S-100 systems (Altair, Imsai, Poly, Northstar) used linear supplies and ran unregulated DC on the S-100 bus. Most designers aimed for +8 to +9 volts to feed the onboard +5 volt regulators (and the3 volt or so headroom for 7805 regulators). Can't think of any that ran high current AC on the bus. Some systems, such as the Poly, ran a squared-up 60 HZ signal for real-time clocks.
The heat losses in S-100 on-card linear regulators were immense! That and the weight of the (linear) transformers helped make the Apple ][, with its switching power supply, so popular (I still have an old Poly power transformer; makes a great doorstop).
Some mainframe computers used the scheme mentioned by others -- polyphase high-frequency AC distribution. High frequency (think 800 Hz) power transformers are small and efficient; that's why switching supplies run at high frequencies (in the hundreds of KHz range).
Efficiency is not only about wasting less power, it's about generating less heat!