Strange CPU reading

[Clearcut]

Hi, I have just built a system with an Athlon x2 quad core 640 - running at 3.0gz . However, I noticed on my CPU usage gadget the following:

I ran CPUZ and saw the following:

The next second it was this:

When I had a dual core the core speed was a constant 3000MHz. Any idea what is going on or if this is normal, as it's worrying seeing the 'clock 780MHz' most of the time.

Thanks for any advice

 

[Clearcut]

Thanks guys, I suspected and hoped it would be something like that. Would you recommend switching it off?

 

[Clearcut]

Ok thanks for your help