CNET reports that IBM and Georgia Tech have coaxed a chip to run at 500GHz, a record for a silicon-based device, by dropping the temperature to minus 451 degrees Fahrenheit:

The experiment is part of a project to explore the ultimate speed limits of silicon-germanium (SiGe) chips. SiGe chips are similar to standard silicon chips, but they also contain germanium for better performance and lower power consumption.

Adding germanium, however, increases the price of producing wafers and chips that come out of the wafers, so SiGe chips are typically only found in a few select markets. IBM has sold hundreds of millions of SiGe chips since it began selling them in 1998, but the cell phone industry gobbles up billions of plain silicon chips annually. (Germanium is sprinkled into standard silicon chips: Intel adds minute amounts of the element to create strained silicon in its processors).

At room temperature, the IBM-Georgia Tech chip operates at 350GHz, or 350 billion cycles per second. That's far faster than standard PC processors today, which range from 3.8GHz to 1.8GHz. But SiGe chips can gain additional performance in colder temperatures.