jazmajor.sir,
I am running the Whisper Rock II right now on my machine but with a couple or three mods:
1. I'm using Arctic Silver 5 instead of the goop that came on the heatsink from the factory. I figure that shaved 1-2 degrees Celcius from the cpu tem.
2. I took off the stock quiet fan and installed an 80x80x25 variable speed fan from my Cooler Master X-Dream original. I run the fan at about 3500 rpms and it isn't too noisy. This probably knocks off 2-3 degrees Celcius.
3. And finally, I made a square tube of cardboard that slips over the cooling fan and extends out a whole cut in the side cover of my case (which also is temporarily a sheet of cardboard). This gives the heat sink fan a fresh, unheated air supply about 15-20 degrees Celcius cooler than the air inside the case. This makes a big difference, probably about 4 degreees Celcius in the CPU temp reading.
Before these mods I was idling my moderately overclocked Tbred at 49-51 and now it's a steady 40 degrees C.
With these mods I've cut about 10 degrees of temp from the CPU.
The Whisper Rock IV heatsink should be a little more efficient than the Whisper Rock II's as it has a copper insert in the base. Either one is a great value but only of you aren't intending to overclock more than a little.
I am wating for the Volcano 12 Extreme which I just ordered. I'm hoping it will knock off another 4 degrees C without having the fan set so high that its anoying.