thats what i thougt of once, and i told it to amd when i met them at cebit. i hope they liked the idear and will implement it. lets say you run an app that is heavily single threadded, then wouldnt it be cool if the dual core cpu would disable one of its cores? then it could clock its first core to a much higher speed still staying in the termal envelope and still using the same amount of energy wich would give you a much better result in that single threadded app than having two slower clocked cores, one pretty much idling and the other one crunching really hard. and as soon as you start another second demanding thread then the core1 clocks itself down to normal speeds and the core2 starts up again and you have two cpus crunching, each on one app
I like that idea and it makes sense. The only reason they are scaling down the core frequencies in the first place is that it's much harder to guarantee two cores that are fabbed right next to each other to have a particular speed bin. It is very likely that when they are making one of these dual core processors rated at 2.4 Ghz, one of them runs just fine at that speed but one barely manages 2.0 Ghz. So they would have to speed bin it down to a 2.0Ghz processor. If this ever happens to be the case, it would be hard to implement what you say as the OS would have to know if one or both of the particular cores are capable of OCing for a single thread.