My 965BE was stock at 1.375v on Gigabayte GA-990XA-UD3. With 1.375 it could do 3.8GHz no sweat, and with a small bump (+0.0125?) it could do 4GHz stable.
But I did not want to overclock, and 1.375v was too much for my liking, so I used PhenomMsrTweaker, and lowered the voltage for each CPU state (P0-P3) individually, at stock frequencies. I can tell you that at 17x200 = 3400MHz (stock) it was stable at 1.2625v, and MUCH cooler (I wanted a silent rig). Even worse, with PhenomMsrTweaker I saw that the same voltage (1.375) was used on ALL states - including 4x200=800Mhz (?)!
Of course, your CPU might take other voltages per frequency, but you could give it a try. If you want, I can give you my table of frequency/voltage as a starting point. And to answer your question, I think 1.488v is a little higher for daily usage if you don't have proper cooling. The temps you give, at idle and load, for 1.488v.. look a little too optimistic
do you have cool ambient temps?
PS: I did not change the voltage in BIOS at all, only trough PhenomMsrTweaker.. The reason was that I wanted to be sure that at boot up I have a "safe" voltage so I don't have to reset all the time the BIOS if anything goes wrong. Plus, the voltages applied by PhenomMsrTweaker are an offset from the values reported by BIOS (so, lowering in BIOS also lowered in this little program, and since I had everything at the limit, in would crash in windows).
EDIT: here's the table:
You have to read it by rows - and the lower ones are for other P-states, with the minimum stable voltage for each combination. The first column is a simple formula - higher clock and higher CPU-NB freq with lower voltage gives a bigger number => should be better.Edited by Paranoid - 11/27/12 at 11:55pm