I have a M4A78T-E motherboard and sometimes have problems with my system freezing or audio stuttering. I usually have asus EPU enabled and set to Auto.
Anyway I have read in and old article here on Tom's that the original EPU was just a software implementation and that in walk mode it would lower the Vcore voltage and this could cause system instability.
I have noticed that Vcore voltage does drop on my rig when in walk mode. It drops from 1.38v to 1.01v. Is this safe? (my cpu is a phenom II 955 )
Also could someone explain to me the difference between asus EPU and what AMD cool'n quiet already does?
Hmmmm, yes I have a M4A79XTD EVO with the EPU-4 engine. I have actually uninstalled it as it really doesnt make a lot of difference to anything. Im not sure if you saw the artical here about Gigabyte showing how ineffective Asus EPU really is but I feel that in the end you have too many programs controlling the system. EPU was overriding my Q-fan which I didnt like and wouldnd always allow the turboV overclocking tool to be used.
EPU does lower the voltage but like you, Im not completely sure how it works, I dont think it lowers the clock, which yes, would make the system not as stable. I have just left AMD cool'n'quiet on as that works fantastically and lowers the voltage AND clock so it is always stable.
So personally I would just unistall it, especially when you see how much energy you are saving...