Last big leap was when when they came up with speedStep technology in Core Duo and Core 2 Duo Processors. Now core i7 will give you 4 cores + 2 threads (HT) on each. So, 8 Threads for your CPU intensive applications: encoding, editing and rendering. So what is this Turbo Mode?
Suppose you have 4 apps eating your 4 cores. Say 3 apps were utilizing the best out of ur each corresponding cores…and this 4th app whos a nerd is not utilizing full CPU, hes utilizing 50% of the CPU capacity at that clock rate. Now what Turbo mode will do is lower the frequency for this 4th core and raise clock for other 3 to boost them into TURBO mode. You save some power from 4th core and distribute over other “NEEDFUL CORES“. Now thats smart. Nice work Intel!
This is just one of the examples, There are multiple aspects of this Turbo mode, the video discusses more about it: