you might want to look at the Skylon cryogenic system and LACE systems. Skylon uses liquid hydrogen to cool the system and the air that it uses to just a little before it turns liquid, while the lace system will cool it until it does become liquid.
http://www.reactionengines.co.uk/
http://www.sworld.com.au/steven/space/lace.txt
and cpu’s can get very hot so you might want to look at the cooling systems designed for them
various liquid cooling
air cooling passive or active( fan, or ionic wind aka plasma)
pelter or other heat pumps to move the heat to cool the important systems
heat sinks
cryogenic systems
thermoelectric, pyroelectric, and other similar systems
