What the hell is "turbo boost"?

[Ravich]

Why have I not seen this talked about before?

[spinnerlys]

Intel® Turbo Boost Technology

Intel® Turbo Boost Technology¹ is one of the many exciting features that Intel has built into latest-generation Intel® microarchitecture codename Nehalem.
It automatically allows processor cores to run faster than the base operating frequency if it's operating below power, current, and temperature specification limits.

via "intel turbo boost"

[beto2k7]

performance enhancer for single threaded apps.

[Hellhammer]

It temporarily shuts down the unnecessary cores and overclocks the remaining cores in order to produce better performance in apps that cannot utilize all cores

http://www.intel.com/technology/turboboost/
http://en.wikipedia.org/wiki/Intel_Turbo_Boost

[CaptainChunk]

TurboBoost has been around since the original Intel Nehalem-core CPUs launched.

Basically, when the CPU detects single-threaded operation, it turns off unused cores to dynamically overclock itself for better performance.

It's supported by Core i3, Core i5 (dual-core models) and Core i7 processors, as well as Nehalem-based Xeons.

[VirtualRain]

Turbo boost is a form of built-in overclocking that Intel has implemented in the Nehalem architecture.

It uses thermal headroom due to a couple of cores being inactive, to increase the clock multiplier on one or two cores that are actively processing, thus increasing their clock speed.

So a CPU that is rated for 2.93x4 can actually operate with 2 cores at 3.3GHz while 2 cores are effectivly shut-down/idle.

It effectively offers the best of both worlds... fast clocks for single-threaded workloads and more cores for multi-threaded workloads, without exceeding the thermal design limits of the system.

It's a great feature.

[Ravich]

oh... so... nothing special if all cores are being used.

[wordoflife]

Originally Posted by Ravich

oh... so... nothing special if all cores are being used.

Not exactly.

If all cores are being used, it can increase too (depending on the processor). For example on the i5-750, if two cores are being used, and two cores are shut off, then it will overclock those two cores to 3.2ghz, but if all cores are being used, it can overclock all cores to 2.8ghz.

Depends on the processor.