Intel promotes the Turbo Boost technology in its new Core i7 Mobile processors as a way to adapt to the needs of the software and get more performance from the chip, but this isn't the real reason the technology exists.
The new "Clarksfield" Core i7 Mobile processors introduced at the Intel Developer Forum last week are certainly very impressive. They're huge high-performance quad-core chips with Hyper-Threading, support for two channels of DDR3-1333 DRAM, and an on-die PCI Express controller for the fastest possible connection to discrete graphics chips.
In his IDF session announcing these parts, Intel Vice President Mooly Eden said the best of these parts, the 2GHz Core i7-920XM Extreme Edition, is "the fastest quad-core processor, the fastest dual-core processor, and the fastest single-core processor"-- all in one chip.
The key to this dramatic claim is a feature called Turbo Boost technology. Basically, if the current application workload isn't keeping all four cores fully busy and pushing right up against the chip's TDP (Thermal Design Power) limit, Turbo Boost can increase the clock speed of each core individually to get more performance out of the chip.
It's easy to see how this works when just one or two cores are being actively used; whatever power the other two or three cores would have consumed can be redirected over to the active cores, allowing them to run at higher speeds.
The quad-core mode of Turbo Boost is a little more subtle; it works when the four cores aren't running a worst-case workload--for example, integer-heavy processing, since it's generally floating-point calculations that consume the most power--so they aren't bumping into the TDP limit. Turbo Boost can increase the frequency of all four cores until they're running as fast as they can for the current workload.
Eden said that the Turbo Boost controller… Read more