Problem and solution, not sure if correct
After upgrading to 5.1 and restarting, lm_sensors complained "General Parse Error." Google pointed here: http://www.lm-sensors.org/wiki/Devices Where I found this under "SENSOR CHIP DRIVERS - STATUS" AMD --> "Since Kernel 2.6.19"
Latest AMD K8 processors have integrated sensors which can be read directly without any additional monitoring chip. Driver contributed by Rudolf Marek. Userspace support available in lm_sensors 2.10.1. Upgrade to lm_sensors 2.10.1 is mandatory, earlier versions of libsensors will fail with a "General parse error" message.
My kernel is "2.6.18-53.el5.centos.plus-i686", but I figured I must of gotten me some backported stuff in there (i.e. I'm in over my head).
I upgraded to the lm_sensors in ATRPMS testing repo, and the problem went away. (lm_sensors-2.10.5-52.el5)