In version 5.0 the opportunity to change the frequency of the processor. Tell me please, will work RB750G at 800 MHz without any problems with stock cooling? Thanks. 
No problem at all.
Can also be changed in 4.xx.
What’s the use? I won’t take the risk to have it crashing for a minimal performance boost.
A better question is what is the risk ? I think it is pretty obvious what the use is.