As processors continue to grow smaller, chip designers are hammering away at the power consumption of those chips while examining power-thrifty methods of increasing performance, according to presentations at the International Solid State Circuits Conference (ISSCC) yesterday.

Microprocessor companies such as Intel, IBM, Sun Microsystems, and Sony sent delegates to this highly technical conference to discuss their latest products and offer suggestions as to what might be coming next. Chip performance has improved substantially in just a few years, but chipmakers are increasingly worried about the large amounts of power required to maintain high levels of performance in ever-decreasing packages.

Intel and IBM presented technical papers outlining their newest desktop processors built on 90-nanometer process technology. The current shift to 90-nanometer process technologies from the older 0.13-micron (130-nanometer) technologies has raised concerns about current leakage, and the topic was a significant part of both companies' presentations.

As lines within chips decrease in size to average widths of 90 nanometers, more electrons are able to penetrate the thin walls and leak out of the processor as heat. Excessive amounts of heat can damage a system, and as chips get hotter more-expensive cooling equipment will be required to maintain performance.

IBM's 2.5GHz PowerPC 970FX – used by Apple in its Xserve G5s – will dissipate about 50 watts of power during typical use, down from 66 watts consumed by its PowerPC 970 predecessor at a lower clock speed, said Norman Rohrer, senior technical staff member at IBM. IBM's chip is also expected to power a new version of Apple's Power Mac.


Power consumption was also a concern for designers of IBM's Power5 chip. That server processor consumes 160 watts of power at 1.8GHz, and while power consumption is less of a problem in the server world, IBM still implemented several architectural changes in order to save as much power as possible, said Joachim Clabes, design-team leader for the Power5.

IBM will release servers built with the dual-core Power5 processor later this year. The new chips will offer 20 to 40 per cent improvements in performance over the older Power4 generation due in part to improved multithreading technology, Clabes said.

Fresh off a large product-launch last week, Sun presented details on two chips that are slated for future products. The company has developed a dual-core UltraSparc processor for dense servers that will consume 23 watts of power at 1.2GHz.

Sun launched its first dual-core processor, the UltraSparc IV, last Tuesday. The new chip will allow Sun to offer blade and small rack-servers with high performing 64-bit chips and Sun's Solaris operating system.

The company has also built samples of a 90-nanometer UltraSparc chip that will use a 4MB Level 2 cache to boost performance. Adding a larger cache to a chip allows the CPU to store increased amounts of frequently accessed data in a repository closer to the processor than the main memory.

Also on Monday, Sony presented a paper on its work reducing frequency and power consumption in system designs for handheld devices, and Xelerated discussed a network processor capable of generating up to 40GB per second of throughput.

About 30 per cent of the total power consumed by Intel's newest Pentium 4 processor is wasted as current leakage, said Joseph Schutz, a vice president in Intel's manufacturing group. This was within the power budget outlined by Intel designers for leakage, but without careful attention to the problem, the current leakage could have been much worse, he said.