Intel Turbo Boost only boosts the speed if the processor is not fully utilized. Their site is pretty vague on details, but I remember seeing that it's designed for when one core is being maxed out while the other cores are sitting idle. If you're using multiple cores, the processor is drawing too much power, or the processor is too hot, then Intel Turbo Boost will turn off and the processor will return to it's normal maximum speed.
All cores will technically be running at the full speed, but you can't utilize all the cores at the same time while boosted or the processor will return to the normal maximum.
Intel® Turbo Boost Technology provides more performance when needed on 4th generation Intel® Core™ processor-based systems. Intel® Turbo Boost Technology 2.0 automatically allows processor cores to run faster than the base operating frequency if they’re operating below power, current, and temperature specification limits.
Any of the following can set the upper limit of Intel Turbo Boost Technology 2.0 on a given workload:
- Number of active cores
- Estimated current consumption
- Estimated power consumption
- Processor temperature
I don't think it will return to the normal maximum if more than one cores are in use. I remember it as having multipliers where the max would ideally be applied for one active core. So in his case, if the normal multiplier were 24 (24 x 100MHz) then the max multiplier would be 34. But if two, three or four cores are active then the multiplier would be something greater than 24 but less than 34, allowing for various boost speeds. – Louis – 2013-06-26T05:14:41.660
@Louis That's entirely possible; That information is more regurgitated from memory when Intel first introduced Turbo Boost, and it's likely that they've refined the algorithm since then. The key is more that while it'll let you push a core past 100%, it won't let you push the processor past 100%. – Darth Android – 2013-06-26T18:50:44.267