The cores inside Barcelona, the quad-core chip coming from AMD later this year, are going to lead independent lives when it comes to power consumption.
The processor, which AMD will discuss at the International Solid State Circuits Conference (ISSCC) in San Francisco, will sport a new version of AMD's PowerNow technology that will let all four cores simultaneously operate at different speeds, depending on their work loads, to curb power.
If one of the cores is running a 3D simulation, for instance, it can crank past 2GHz, while the other three can slumber at 1GHz. The cores can run at one of four different speeds.
In current AMD dual-core processors, the two cores can run at slower-than-maximum speeds, but they move in tandem. By making the speed of each independent, AMD has cut the average power consumption of Barcelona by about 10 watts, said Brent Kirby, product manager for servers and workstations at the chipmaker.
ISSCC is one of the premier events every year for semiconductor designers and researchers. At this year's conference, IBM plans to describe a Power 6 processor that can exceed 5GHz, while Intel will go into more detail about the 80-core processor it showed off last autumn.
The conference has played host to several significant announcements in the past. Papers that first described digital signal processors (from Bell Labs in 1980), RISC chips (from University of California, Berkeley and Stanford University in 1984), 100MHz processors (Intel in 1991) were published at the conference.
Still, the bulk of the papers — such as the one titled "5mA 0.6 CMOS Miller Compensated LDO Regulator with a -27db Worst Case Power Supply Rejection Using 60pf On-Chip Capacitance" from the Georgia Institute of Technology — go far over the heads of even the technoliterate.
As for AMD, it has also improved the circuitry in the integrated memory controller so that the read and write functions in the controller can be shut down. The improvements can cut power consumption in the memory controller by as much as 80 percent.
Additionally, the memory controller and the processor cores can be independently powered up or down. Thus, the memory controller will work at high levels if one core demands it. This safeguards against performance declines, Kirby said.
As a result, Barcelona, although it has twice as many processor cores as current high-end Opterons, can fit into the same servers. Barcelona chips will have a thermal envelope — or maximum power consumption — of 68 watts, 95 watts and 120 watts, depending on the model. (Faster chips consume more power generally.)
