The shrinking size and increasing power consumption of electronic products also make their thermal management challenging. Poor thermal management results in increased temperature of the electronic component, ultimately leading to the failure of the element. Thermal management of electronic devices is assisted by passive techniques such as heat sinks. Phase change material-filled heat sinks attract industries, as they are compact and do not require frequent maintenance. In this study, heat sinks with internal surface modifications, i.e., engraving and grit blasting, are developed. The heat sinks are provided with heat storage mediums like paraffin wax and nanoparticles to analyse their effect on thermal management. This study employed two different nanoparticles, i.e., silver titanium dioxide and graphene. A simple heat sink without surface modification and a heat storage medium was used as a reference. It was found that using graphene-mixed PCM in the smooth heat sink increased the charging time by about 8%. Adding graphene nanoparticles to the phase change material decreases the discharging time by about 29 %. Grit-blasted heat sinks took the most time to discharge, followed by base-engraved heat sinks. This is because the internal surface roughened heat sinks stored more heat energy during the charging process. Adding graphene nanoparticles to the PCM increases the duty cycle by about 40 %. When used with paraffin wax, base engraved heatsinks and grit-blasted heat sinks have increased the duty cycle by 11 % and 36 %, respectively.