This paper reports the thermal behavior of Phase Change Material (PCM) based heat sinks with different Thermal Conductivity Enhancers (TCEs) for constant and power surge heat loads. Three types of TCE configurations, namely, vertical pin fins, baffles, and a combination of fins and baffles, are considered. Heat sinks and TCEs are made of Aluminum. The effects of Surge Duration (SD) and the Surge Interval (SI) on the thermal performance of the heat sinks during a constant 10 W heat load are experimentally investigated. The surge durations are 5, 10, 15, 20, and 25 s, whereas the surge intervals are 100, 150, 300, 450, and 600 s. The surge amplitude in all the cases is fixed at 50 W. The operating time and efficiency are the two metrics used to characterize the heat sinks. Eicosane, Docosane, and Tetracosane with melting point temperatures 36-37 °C, 42-45 °C, and 49-52 °C, respectively, are considered as the PCMs. Vertical fins perform better than other TCE configurations considered in this study, in regulating the heater temperature as well as in increasing the operating time, for all the three PCMs when subject to both constant and power surge heat loads.