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.
Now, the oldest overclocking trick in the book is to take a CPU and pump up the voltage to make it run faster. If you want your P4/3.0 to be a P4/4.0, you up the power and pray that the smoke does not get out before you can run SuperPi. The same thing is true for console CPUs, if you want more of them to run at a clock of X, you relax the power requirements.
So, for the XBox CPU, if you want higher yields, you bump up the power. If you are Sony, and you want to know what the Microsoft yields are, you can figure out a good portion of this if you have the power consumption numbers. If you are Sony and you know the yields, you can better attempt to pull sleazy pricing games on Microsoft.
So, basically, power consumption numbers equal better marketing for the competition. The same is true for the PS3 CPUs and MS's marketing. Basically, it is the missing piece in the whole backstabbing campaign, and the less of a clue MS can give Sony, the better for them. To close, the numbers I have heard for Waternoose are 80W and 110W, but I don't have a clue if either one is correct. One thing for sure though, the Sony already has several in the labs, and it has more than a clue now.
The INQuirer
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