How to predict MTTF of CPU and other cards using the MIL-HDBK-217F?

Another approach is to use real-life information gathered from systems in operation in the field. Using information such as number of failures, or number of repairs, downtime, time to repair, etc., values such as MTBF and MTTR (Mean Time to Repair) can be calculated. Another approach is with the use of part count prediction; the part stress is generally used to analyze electronic circuits in the early design phase when the components' data and design stress data are available (from the manufacturers or other way). In the case of CPU, the major factor that influence a CPU (Integrated circuits) are Temperature, Supply Voltage, and the package type. Other data that influence the CPU Reliability are the Power dissipated, number of pins and some other parameters. The Bellcore method part models were originally developed for commercial applications, however you can use also the S217 method  for commercial application.