Differance from fast and turbo mode

[fstime]

Can some please explain to me the differance from fast and turbo model. The only thing I notice is that on turbo mode I get a +5-10 degress in my CPU temp. What does the switch to turbo mode do exactly?

 

[fstime]

By the way, it is a MSI k8t-neo mobo on an AMD athlon 3400+ 64