
Though it might seem fun to try, you shouldn’t pour oil into your PC case or overclock a CPU to 5GHz using dry ice for safety reasons.
Oil-Cooled PC

Though it’s been done before, Tom’s Hardware has created their own nifty oil-cooled PC, enclosed in a clear case and filled with “8 gallons of cooking oil to improve it’s cooling”.
Indeed, the large volume of liquid guarantees absolutely silent operation – no fans are running. And even under maximum load the three major building blocks remain sufficiently cool: processor, graphics card and chipset.
[Source]
5GHz Project

Tom’s Hardware “set out to squeeze at least 5 GHz from the selected Intel P4” in this classic test.
Finally, by gradually increasing FSB speed from 200 MHz (factory setting) to 309 MHz, we achieved a record speed of 5255 MHz. At full load, taking into account a maximum CPU heat dissipation of just under 175 watts, we recorded a temperature of approx. -190°C on the CPU cooling head