In Military, Medical, Space, Professional equipments design there is a need to be able to prove that the devices can last a certain length of time with a certain confidence level. Or that reliability must be used in design to inform the design direction, either through component selection, component testing and sort or in amelioration techniques (like redundancy, FEC - Forward Error Correction and so on). A higher level of reliability became a compulsory demand in modern DC-DC converters. Since the latest version MIL-HDBK-217F Notice 2 released in 1995, newer failure rate prediction standards had appeared on the electronic systems reliability market. These are introduced to compensate for the lack of the newest component technology in the above-mentioned standard. When it comes to reliability many studies have shown that the output capacitor bank is demonstrated to be the most critical component. In this work, the failure rate of an output capacitor bank and MOSFET transistor pair used within a high current low voltage buck converter is calculated both by the latest prediction standard SN 29500 and by with the previous standard MIL-HDBK, providing a comparison between the two which is a helpful tool for the output capacitor selection in the early stage design. Both simulation and experimental workbench set-up for the converter was used to detect the temperatures of the components. The SN 29500 standard is particularly useful for components used in harsh environments, providing up-to-date failure rate data and stress models. The components’ environmental conditions were defined by a standard PoL buck converter used for both calculation methodologies. Results are compared by taking account of the influence of the component’s temperature and application of specific parameters such as reference conditions and operating conditions.