Is it possible to drill a CPU cleanly with a plasma cutter? I would like to know if it is possible to cut a clean hole into a standard CPU with a plasma cutter, without damaging the plasma cutter. 

I am making CPU keychains but I need to drill a hole through them first. If it is possible, it would make it way more efficient.
Use a diamond drill bit. Cheap plated bits are good to learn on, but if you're doing it a lot, invest in sintered. Look at a lapidary or jeweler supply store/site or eBay