Why Microsoft won't give XBox360 power numbers

"It is all about yields

When IBM gave out the info on the XBox360 CPU, there are two things it would not reveal, its name and the power consumption.

Well, the name part is pretty well known, it is either Xenos or Waternoose, but you can understand why in this litigation crazy day and age they wouldn't want that out. The power use is a little stranger, but like the three cores, has a reasonable explanation.

The reason is console pricing, about the last thing you would ever think of when quoting CPU power consumption. The console business is a harsh one full of backstabbing, loss leaders and competitive pricing. Long before a console is built, the first few shrinks, component costs and price drops are already planned out. The same is true for the competition. If Microsoft is going to cut the price by $50, you can bet Sony will match it, and you can also bet if it is able to dig a heel into Sony with said cut, it will time it to do so. If Sony sees a gap, it will likewise go for the throat.

Now back to the point. The most costly components of a console are the CPU and the GPU, probably in that order. When you are looking at the cost of a CPU, there are the static costs, that is design, and the production costs. The production costs are dominated by one thing - yield. If a wafer costs $10K to run through the fab, and you can potentially get 200 good CPUs out of it, each one costs $50 at 100% yield. At 50% yield, you get a cost of $100.

Now, there are a few things that affect yield. The first is defect rate, whether it works or not. The second is the speed at which it can run, when you see a Pentium 4 at 3.8GHz and another at 3.6GHz, it isn't because Intel wants to sell you a range of options, it is because they have so many that will run at each speed, and price them accordingly. Consoles don't have the luxury of multiple speeds, they run at a frequency, and will run at that frequency for their entire life. A console CPU will run at that speed or it will not, and if it doesn't, there is not much use for it." [more]