The influence of non-uniform heating conditions on the buoyancy-driven flow established in an open square cavity with ventilation ports is studied. Cavity configuration is shaped to electronic device with passive cooling. Numerical results for relevant parameters are presented as a function of the Rayleigh number, considering both fixed temperature and heat flux heating conditions. The results obtained retaining the temperature-dependent thermophysical properties are compared with those calculated under the Boussinesq approximation. The impact that the non-uniformly heated wall produces on the thermal and dynamic behavior of the airflow is analyzed. The choice of a given heating distribution slope can produce a thermal behavior improvement, even increasing heat transfer above 20%. Some practical engineering correlations are presented. In fact, a correlation for the critical heating parameter for isoflux heating condition, concerned to the burnout phenomenon, is obtained from numerical results. The effects of the non-uniform heating condition (heat flux case) are not too relevant on this particular phenomenon.