Linked by Nicholas Blachford on Wed 9th Jul 2003 16:43 UTC
Talk, Rumors, X Versus Y This article started life when I was asked to write a comparison of x86 and PowerPC CPUs for work. We produce PowerPC based systems and are often asked why we use PowerPC CPUs instead of x86 so a comparison is rather useful. While I have had an interest in CPUs for quite some time but I have never explored this issue in any detail so writing the document proved an interesting exercise. I thought my conclusions would be of interest to OSNews readers so I've done more research and written this new, rather more detailed article. This article is concerned with the technical differences between the families not the market differences.
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Power consumption is a very complex field. There are more than one or two facts which describe why a processor consumes more or less power. Nicholas writes that Intel uses high speed transistors which consume more power. This is true, that faster transistors can waste more energy. First, leakage current is higher and second, you have to overload the base of the transistor by using higher voltage for make it switch faster (oversaturation). But on the other side for reaching higher clock rate you can make transistors smaller, you can reduce your voltage, because a smaller transistor needs less electrons inserted into his base area for reaching saturation.

A great power consumer is the clock tree. Alphas are very power hungry due to their clock tree which is a mesh with a very high capacitance. So to make the clock tree switching fast, a lot of power has to be pumped. I don't exactly know which clocking structure uses Intel on his chips.

All I want to say is, that the reasons why x86s are power hungry have to be more diversificate than just the fact that Intel probably uses high speed transistors.

Greetings from Anton