This work focuses on a comparison of second law based component design on one hand and second law based system design on the other within the context of electronics cooling. Typical electronics cooling components such as a heat sink and a heat exchanger are modeled and designed towards minimum entropy generation on individual level and on system level. A comparison of these levels allows us to qualify and quantify the influences among components induced by a system. Simultaneously, this article endeavors to be an illustrated assessment of the usefulness of efficiency criteria on component level. It turns out that the results of this work reveal a substantial influence of system dependencies on the optimal component design. As such a note of caution is raised about second law based component design which does not take into account the system in which a component has to operate.