Fast Forward: Low-Power Newbie: the x86

Nathan Edwards

In the microprocessor universe, there’s low power and then there’s low power. These days, a desktop PC processor may be called low power if it consumes less than 100 watts. Notebook processors use tens of watts. But for some systems—especially ultramobile devices expected to run for days on a battery charge—low power means one or two watts, or even less.

The x86 architecture, king of PCs, is largely absent from the true low-power realm. Tear down a cell phone, iPod, or digital camera and you won’t find an x86. Most likely, you’ll find chips based on a 32-bit British RISC architecture widely licensed by ARM. The x86 is popular with developers, but it’s too hot for your pocket.

Now there’s change afoot. Intel and VIA Technologies are introducing new x86 chips designed to push the architecture into consumer electronics and other products in which lower power is a requirement. Actually, VIA has been doing this for 10 years with its Centaur Cx-series processors. But VIA has won minuscule market share and scant brand recognition outside the semiconductor industry. Now that Intel is entering the low-power x86 derby in a big way, things may change.

Intel’s entry is code-named Silverthorne. It’s a fully compatible x86 processor that initially slashes power consumption to the one- or two-watt range. Future versions, Intel says, will run at 2.0GHz while burning less than one watt. Early samples are already in customers’ hands and appeared in prototype products in January.

VIA’s contender is code-named Isaiah. It, too, is a fully compatible x86 design. Initial chips will burn less than 3.5W at 1.0GHz and appear by summer. VIA claims to measure power consumption more rigorously than Intel does and says that Isaiah is more competitive with Silverthorne than the prerelease numbers indicate. But Intel has a clear manufacturing advantage. Silverthorne will debut in Intel’s latest 45nm high-k metal-gate fabrication technology, whereas Isaiah is manufactured in an ordinary 65nm bulk-CMOS process.

Intel and VIA are taking different approaches with their new x86 designs, which I’ll cover in future columns. Neither design is as power-stingy as ARM’s smallest processors. However, the big news is that the x86 is moving in a new direction—into your pocket.

Tom Halfhill was formerly a senior editor for Byte magazine and is now an analyst for Microprocessor Report .

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