The 5.0 GHz is the upper limit for the CPU, and it will only be reached if the system demands it, AND only on one core -- if you're running on all cores, you will never see 5.0 GHz.  
Hi Guys, I have an Alienware 17 R5 with 2.9GHz and 5.0GHz Turbo. I am assuming that if I run 5.0GHz, the laptop is built to handle this without harming the processor? Does anyone have advice on this issue? Thanks, Chris
17 R5, 5.0GHz Turbo usage?