[A//// Guy]

APC makes units that are external and hook up to the UPS's, and then the UPS is connected to your server through usb or serial. We are using one of their temp/humidity sensors in the server rack and it notifies you however you want if the temp/humid is too low or high. This is only for external temps though, you put the sensor wherever you want. You can use software like the ones mentioned though to keep tabs on the actual core temp.