Considering its impossible to get sub ambient temperatures without an active (peltier, LN2O, etc) coolers, you are using a program incapable of monitoring FX temps properly.
Use AMD overdrive and look at the thermal margin, that is the only accurate way to check FX series temps.
To answer your question, its impossible with a conventional setup to have a processor be "too cold", thats just a result of the program reporting wrong temps.