Intel Core i7 Weird High Clocking Behaviour

[EliaBordin]

I need help in understanding one simple thing that I find difficult to realise of my CPU.
I own an ASUS K56CB with 8GB RAM, 1TB HDD+24GB SSD, Windows 7 64-bit, motherboard ASUS K56CB 1.0. My BIOS is fully up-to-date, and, except my battery which has stopped working, this laptop works fine.
I am not a wealthy-enough person to buy "spare parts" for my laptop to test it.
The problem I am encountering features my CPU, an Intel Core i7 3537U which is designed to run at 2GHz, as the benchmarks state.
Some time ago I noticed how the "System Information" windows in the Control Panel states the following on the "Processor" line "Intel(R) Core(TM) i7-3537U CPU @ 2.00GHz 2.50GHz" and I always asked myself why does it have 2 clock speeds.
Today, having some spare times, I wanted to go in depth, and downloaded CPU-Z and discovered that the clock speed fluctuates between 2893.10 MHz and 3092.63 MHz, which is much over than both 2 and 2.5GHz. Is this normal? I never practiced overclocking.
Thank you in advance for your help.

 

[EliaBordin]

Oh I was forgetting: I occasionally get a BSODs (1/month) and, when they occur, they are always of code 0x00000124 (hal.dll main problem, then ntoskrn.exe is also considered problematic, BlueScreenView highlights them both red). I know it is a hardware issue but I don't know what is it related to, maybe to this?