Heat gun (can be subbed out for hair dryer), thermal double sided tape/pad, paint. Put the ram on a flat surface.
Hold the heat gun at least 5 inches away from the ram. Turn on the heat gun (low) and pan the heat gun from one side of the ram to the other until the ram is hot to the touch (not burn to the touch but just hot enough). Once hot to the touch, use a flathead and carefully pry the heatsink/casing apart from the ram. The slower the better.
If you want to reuse the thermal pad I advise you to peel the heat sink off slowly. Go to a local metal works company and ask to see if they can sand blast the heat sink. Once sand blasted, spray the heat sink with heat resistant paint (any kind, I prefer to use airbrush powder based paint). Then let it sit for at least an hour. Put the thermal pad back on carefully making sure it's not touching the ram pcb or anything that can short the ram.
Put the heatsink/casing back on. Now your're done.