I just finished my build and stressed the Phenom II x4 955 3.2Ghz CPU with Prime95. I monitor the CPU temps with my Mobo (MSI 890fxa-gd70) which has a handy LED display. The lowest I've seen it hit is 26C with the fan at ~3700RPM but when I stress it to 60C (the highest I've seen it) the fan hits only ~4100RPM. What does this mean? Is the fan not being controlled properly? Does this have something to do with AMD Cool 'n Quiet? Also, are these good CPU temperatures? Thanks for the help, this is my first build and I'm kinda paranoid about the temps.
First off, did you read the manual for your cooler (is it a box-cooler or aftermarket)?
In my opinion, 4000RPM is probably the upper-limit for that fan speed. It probably just can't go any faster. As for 60C, this shouldn't be too much of a problem if that's as high as it gets, and only if it gets that high under extreme loads. The fact that you've seen 26C indicates to me that it is receiving the proper amount of cooling. In fact, I'm more intrigued that the fan wasn't turning slower at that temperature. My fan will range from about 1200-4000 (Thermal Take Mini-Typhoon). So no, I wouldn't worry about 60C. Now, 80-90C, that could indicate a problem.