Virtual Consumer Sep-Oct 2008

Hot chips

Column for Ethical Consumer Magazine Sep-Oct 2008

Shaun Fensom explains why computers use more and more power

Since the first microcomputers became available in the 1970s they have been getting faster and more powerful at an astonishing rate. From an environmental point of view this has two important consequences. Firstly, obsolescence: computers are frequently discarded after just 2 or 3 years, generating an ever increasing quantity of hazardous waste (I shall return to this issue in a future column). Secondly, energy: more powerful computers use more electricity.

The founder of Intel, Gordon Moore, suggested in 1965 that the number of transistors that could be fitted on a silicon chip would double every year. In 1975 he changed his mind and said it would double every two years – still a remarkable notion. Remarkable also in that he turned out to be right – people nowadays refer to “Moore’s Law”. The world’s first microprocessor, the Intel 4004 launched in 1971, contained 2,300 transistors; now 37 years later the Quad Core Intel Xeon has 1,328 million – corresponding very neatly to a doubling every two years.

But while engineers have been squeezing more and more components into a smaller space, there has also been a race to increase speeds. Here a similar “law” applies with speeds of the central processor doubling every 1.8 years. Higher speeds mean more functionality and ease-of-use. The shift to easy-to-use “point-and-click” interfaces in particular has required much faster processors.

Speeds have been increased by shrinking the size of the components on the chip (so that the signals have less far to go), but also by increasing the operating voltage and “clock speed”. Double the voltage and you quadruple the power consumption, power that ultimately becomes heat. So computers have been using more and more power, and the processors have been getting hotter and hotter. The very first personal computers could be left to cool themselves. By the 1980’s they had fans to circulate air round the components. Now desktop PCs have massive fans that blast air directly at the processor itself. The problem takes on nightmare proportions once you start squeezing hundreds of computers in a data centre.

Now there are signs of change. Intel has abandoned its strategy of squeezing more and more instructions per second out of a single processor in favour of using Moore’s Law to put more processors on a chip to share the work, with “dual” and increasingly “quad” processor chips now commonplace. This still increases power consumption, but not so quickly. It also opens the route to new “ultra low voltage” chips that run cooler and slower, while maintaining overall performance.

A typical desktop PC (excluding the monitor) will consume more than 100 watts while busy and can average more than 70 watts. Now new manufacturers like Very PC in Sheffield are offering high-spec desktop PCs that average under 30 watts. And if all you need is basic computer functions CherryPal have announced a machine that consumes just 2 watts – although you still need to add the monitor. Green IT is beginning to come of age.