Solid Solid phase change materials (SS_PCM) based thermal management systems (TMS) integrated with heat pipe are considered as excellent passive thermal management solution for electronic packages. To enhance the thermal conductivity of SS_PCM, nano-enhanced solid-solid phase change material (NE_SSPCM) samples were prepared by incorporating Neopentyl Glycol (NPG) with 1 wt.% of Graphene nanoplatelets (GnP), Copper oxide (CuO) and Aluminium oxide (Al2O3) nanoparticles separately and its thermophysical characterisation study was performed. NE_SSPCM packed heat sink integrated with heat pipe was tested at different power levels from 9-13 W and its thermal performance was compared with TMS based on Empty heat sink, PCM-packed heat sink and PCM-packed finned heat sink configurations. TGA and FTIR characterisation techniques revealed good thermal and chemical stability for all NE_SSPCM without affecting the structure of NPG. DSC showed reduction in phase transition enthalpy for NE_SSPCM than SS_PCM. Thermal conductivities of NPG with 1 wt.% of GnP, CuO and Al2O3 nanoparticles improved with relative enhancement ratios of 1.8, 1.5 and 0.8, respectively. From the experimental analysis, NE_SSPCM with heat pipe configuration showed outstanding average improvement by 7, 4.3 and 4.2 times at 9-13 W. Additionally, by extending safe operational period, all configurations were more effective at lower heat generation rates. In contrast to three nanoparticles, GnP based NE_SSPCM showed outstanding average improvement of 1.8 over NPG for PCM-based configurations. The study concluded that implementation of GnP in SS_PCM assisted heat sinks with heat pipe exhibited maximum enhancement ratio of 11.3 and demonstrated remarkable efficacy in all aspects.