If you're talking about taking the computer into cold climates, as long as the computer is completely disconnected form power while it is cold, the computer won't be damaged. MAKE SURE to let the computer come back up to room temperature before you turn it on; a good rule of thumb is to let it warm up for at least as long as it's been outside.
If you're talking about using refrigerants to actively cool the PC, then you're going to want to use insulating or sealing materials to make sure water doesn't condense on any conductive parts.