The name is somewhat deceiving, Turbo Boost, it works like this. When your CPU is idle it can sit at that 3.8GHz because it has no load and will give you snappier usage of your PC, but, it will throttle when the PC starts to heat up with your workload, and the if CPU Temp begins to rise higher than what it should be your Turbo will go away, and if cooling is not sufficient, it will actually go below stock speeds. And lifespan is no issue, it is simply at a higher clock rate.