Explo :
I thought it might be more efficient? If I did turbo, I'd be doing exactly what they do in the THG overclocking review that was recently posted. If the chip is intelligent about what cores are being used and when, wouldn't it be worth it to have it switch automatically between, say, 4.5ghz across all cores or 4.6 across three, 4.7 across 2, or 4.8 across one, all with the same low voltage?
I guess it comes down to how well it detects core usage?
The fantastic thing about these K series is you have that option, you can go the Turbo enabled or not it's really up to you, if Turbo is enabled you have the flip side of the coin I don't care for, it will idle down to 1600mhz for the 2500K at that point the desktop is sluggish and slow to respond, until you run a solid power drawing app., that causes it to kick back up to at least the default 3300mhz.
With Turbo completely disabled and the features that work with that feature also disabled, and all 4 cores enabled the desktop experience is amazing and seriously tends to spoil you at the responsiveness of everything, you'll probably be going both routes and answering these questions for yourself.
For example if you run a 45X multiplier, all 4 cores will run at 4500mhz as long as they're being supplied the proper voltages to maintain that level stably, however it's imperative you have extremely good after market cooling, because under load those temperatures have to stay below the Thermal Throttling Threshold.
So it really boils down to how important is the power saving features to you, most of us previously overclocking AMD Black Edition CPUs, right out of the gate disabled every Cool and Quiet and CPU throttling feature the CPU had, so this is literally the same type of overclock to disable all the power saving features of the K series, to result in a straight across the cores clock.
The choice is yours, it's a new platform, do your own tests.