Dry ice is solid CO2. Its compressed and cooled from a gas too a solid. Too remain as a solid it needs too be kept cool. And therefore, at room temperature it starts changing phase from a solid too a gas (sublimates). To achive this it needs heat. Wich it will take form any availbie source. Ususaly the surroundings. But using special containers known as slugs, its used too cool cpus too rediculously low temps.
Ill dig out a PT chart wich will show some of the latent temps....
Lol, i just spend too much time reading PC stuff .
Ive never dabbled in this kind of stuff (...yet).Its quite costly and the risk to hardware is huge. Gonna concentrate on my phase before i try anything like this myself.