Submerging your PC in cooking oil seems like one of the worst ideas ever suggested, but it’s been done by the guys at Tom’s Hardware. Turns out that oil is a pretty good coolant, and as it doesn’t conduct electricity, won’t short out your components.
The associated Digg story links to a few other people who have tried similar things. My personal favourite is this one – in my opinion, he’s done a better job by avoiding the gratuitous use of silicone sealant and employing mineral oil to improve visibility and presumably reduce the chance of the oil becoming rancid. I also like the airbrick which sends bubbles up through the case.
I’m interested in trying something similar – I replaced my graphics card today and stuck the old card’s fan in a pot of sunflower oil. When I powered it up, it started spinning as normal, although silently and a lot less quickly. I’m not ready to rebuild my main PC in a fishtank full of baby oil, but I’m tempted to drag an old junk PC down from the loft and see how it fares as a silent, oil-cooled system.
Note that it’s unlikely that you’ll end up with a completely silent system – certain components such as the drives and power supply are definitely best kept out of the oil – but you can at least reduce fan noise and maybe even improve cooling at the same time.
Obviously, experimenting with cooling-by-oil-submersion is not without its risks – there’s a chance that you’ll fry (no pun intended) your system and/or end up with a pool of oil on the floor – but you can certainly have fun trying.