Increase your iMac's multitasking ability by adding RAM, allowing more programs to run at the same time. Speed is negligibly affected.
Lay the iMac display-side down on a flat surface.
Loosen the three Phillips screws securing the rear panel to the iMac.
Lift the rear panel slightly from the bottom edge of the iMac.
Pull the rear panel toward yourself and remove it from the iMac.
Rotate each of the two RAM retaining arms away from the RAM chip.
Pull the RAM chip straight away from its socket.