Intel tries to keep its cool

Steve Pawlowski, the director of Intel Corp.'s Microprocessor Technology Lab, knows Intel has a heat problem.

As processors like Intel's Pentium 4 have increased in performance and power, they've also become generators of intense heat. Pentium 4 chips currently generate more heat than a kitchen hotplate and the company's projections show the heat generated by its processors will increase sharply in the coming years, perhaps rivalling the core of a nuclear power plant, unless solutions can be found to the problem.

The heat problem also has short-term implications. Growing demand for notebooks and computers used as home entertainment centers means Intel has to find ways to reduce and dissipate heat more efficiently and more quietly than ever before.

"As Intel keeps increasing the speed (of its processors) that generates more heat," said Dorothy Lai, a semiconductor analyst at Garner Group Hong Kong Ltd. "The problem is that you can make a very big heatsink but you cannot use a very big heatsink as the product (PCs) is getting smaller."

Faced with this challenge, Intel's engineers are looking at several different approaches to reduce the amount of heat generated by processors and to dissipate that heat more quickly, Pawlowski said.

However, engineers have a limited set of options that are available with current technologies and chip designs. For example, they can adjust factors such as clock frequency, voltage and capacitance -- the ability of a device to hold an electric charge -- in a bid to reduce the amount of heat that a processor generates.

"You can either drop the voltage and you get a quadratic improvement in terms of power, drop the frequency or don't increase the frequency as much, and of course you can decrease the capacitance, if that's possible," Pawlowski said, speaking on the sidelines of the Intel Developer Forum in Taipei.

Engineers can also look to external devices that help dissipate the heat generated by a chip more quickly. In this area, Intel is investigating the use of improved cooling fans, impellers and other devices that can help keep processors cool.

But these improvements are constrained by other factors, such as the packaging used to encase the silicon component of a chip.

"There's a certain transfer coefficient between the die and the package," Pawlowski said. "If you can't come up with a better package that will allow that heat transfer to occur from the die, no matter what you do on the outside, its going to be difficult." Die is a term that describes an unpackaged piece of silicon that contains an integrated circuit.

"I think we're going to have to look at architectural solutions in order to try to minimize the heat as much as possible," he said.

Microarchitecture is important because heat is not generated uniformly across a die. A single die contains many different electrical components, such as logic and memory, which have different activity levels and generate different levels of heat. For example, memory generally has a lower activity level than logic and therefore generates less heat. By the same turn, some logic components generate less heat than others.

By spreading out the hottest components on the die, chip designers can help dissipate that heat more efficiently but this still doesn't eliminate the existence of hot spots on the die.