As power dissipation of electronics increases in parallel to the miniaturization pressures on these same volumes, previous rules of thumb and myths involving system level thermal management and cooling need to be challenged to ensure a valid overall packaged system solution that meets the overall function and environmental requirements. These misconceptions and myths arose when today’s decision makers were just entering the electronics packaging industry. The capability of the electronics, their packaging density and power dissipations are much greater today, so these previous rules of thumb no longer apply. These misconceptions are that: (1) Natural Convection is always available to be used; (2) Thermal performance is only an issue for the chassis design; (3) Power is the only board information that is required for chassis design; (4) Heatsink and Thermal Interface Materials (TIM’s) can solve any thermal problem. (5) CFD is sometimes thought of only being colored pictures for directors but it can be a valuable tool for thermal management. The source of these myths and misconceptions is discussed and the challenging of these myths and misconceptions provides a path to understand today’s thermal management issues and how to ensure that they are addressed up-front in product planning.