Originally posted by: Idontcare
No one wants to project to their shareholders a business plan that is relying on a steady-stream of broken parts.
Look at the GeForce 8800 GTS. It's based on the G80 chip with four clusters of 32 stream processors, but one of them is disabled. And it's insanely popular.
And it doesn't have to
rely on a stead stream of
partially defective parts. If you have more working quad-cores that's a good thing, and you can lower your quad-core price so more people buy it and you don't run out of triple-cores.
...but customers don't like the perception they are buying broken stuff or someone else's garbage so you better control the PR...
Most people won't know a triple-core has four cores with one disabled. And again I refer to the 8800 GTS. Nobody cares it has 1/4 disabled. They rather buy this one than a chip with two working clusters. As long as the price/performance is right they won't feel like buying broken stuff.
BUT it must be part of a grander business plan that entails supporting that product over the long run.
Why? In my local store I've seen Celerons and Semprons come and go. As long as I can buy a well-performing CPU for my budget I'm happy. I'd rather buy a triple-core than spend too much on a quad-core or get only half the performance with a dual-core.
ONLY in that environment would you say "hey I can save 6 months in my launch timeline if we start with recycling broken chips while the layout guys finalize their plans on the dedicated triple-core celerons".
If it's correct that broken dual-cores are now being sold as single-cores I doubt they won't have thought about how to properly disable a broken core in a quad-core.
That is how you get celeron products at launch that are merely cache-disabled versions of the premium product but then 2-3 quarters later the "real celerons" show up with die size reductions that can be leveraged into cost savings AND the shareholder feels your business model is sustainable.
Actually with new silicon processes and even higher number of cores I believe you can 'sustain' that business model. The PlayStation 3 is equipped with a Cell processor with only 7 out of 8 vector processing cores enabled (even if all eight work). Intel and AMD have a lot more freedom by just pricing them differently.