When using Intel's Turbo Boost monitor, very rarely does it hit the maximum 2.9GHz.
Like right now... I'm using Handbrake to convert some videos. All 4 processor cores and all 8 threads are being used. I just noticed that my CPU is over 85C, so I cranked the fan up all the way. Anyway, the monitor is going from 2.30GHz to 2.50GHz, but never higher. Why is this? Some games will make it stay at 2.6GHz.