Power cord to power plug circuit board
There are three screws keeping the fan into place with the heatsink. Two of them can be easily removed, the third one due to poor motherboard design layout needs you to completely remove the heatsink in order to unscrew it. This is why you also need to re-apply the thermal paste.
Pavilion CPU processor, video card and northbridge chipsets exposed
Closeup of the CPU processor and northbridge chipset