Method, system and article of manufacture are provided for continually monitoring reliability, or aging, of a digital system and for issuing a warning signal if digital system operation degrades to or past a specified threshold. The technique includes periodically determining a maximum frequency of operation of the digital system, and generating a warning signal indicative of a reliability degradation of the digital system if at least one of: (i) a measured or estimated maximum frequency of operation of the digital system is below a warning threshold frequency of operation of the digital system, wherein the warning threshold frequency is greater than or equal to a manufacturer specified minimum frequency of operation for the digital system; or (ii) a rate of change in the difference between measured maximum frequencies of operation of the digital system exceeds an acceptable rate of change threshold for the digital system.