Readers' Responses to Strip Out The Fans, Add 8 Gallons of Cooking Oil

Mr Rudolph Opines: Solid Fat At Room Temperature

Good morning:

I find your oil-cooled PC project fascinating, but I have a couple of ideas and questions I'd like to share on this subject. A nice gimmick would be some kind of long-chain fatty acid, because it would be solid at room temperature, making transport of the PC much simpler and easier.

I would recommend stearin (C16) or palmitic acid (C18). These are saturated fats that are very stable, and that give off no (or only a very few) H+ ions. If these substances melt too slowly, however, it might make sense to use a C14 or C12 fatty acid instead. To protect the Plexiglas, you could also coat it with an emulsifier (by painting it or using a film of some kind) to repel the fatty acid itself. With a chemist at your disposal, you should find it no trouble to brew a fatty acid that would be liquid at 84° F (30° C).

At the end of your article you recommend motor oil. Should you use completely- or partly-synthetic oil? I would be sure to check to see if I can also build something like this for myself. It would certainly be the prime attention-grabber at any LAN party, if you were to show up with a PC deep-fryer. If I come up with any new ideas, I'll be sure to get back in touch!

Best wishes,
Urs Rudolph

E-mail From Mr. Wimmer: A Special Coolant

Hello Mr. Völkel,

I found your article about the oil-cooled PC very interesting. I had already thought of immersing a complete PC system within a fluid of some kind myself, primarily as a way to stymie noise output. That was a thought that had long since vanished from my musings, however.

I have a couple of thoughts as they relate to your test. Sadly, the choice of oil as a coolant is not the best option. I have worked for a while now on the development of temperature measurement systems for semi-conductor production. This permits the wafers to be cooled to temperatures as low as -76° F (-60° C). For many tests, this makes absolute electrical isolation of the carrier substrate from the local environment possible.

For our coolant, we use a special fluid named "Galden ZT 150". This fluid is colorless and looks better than vegetable oil in every situation. It's also completely neutral chemically. In addition this fluid possesses phenomenal volume resistivity of 2.0 * 1010 Ohms/cm. This makes sealing up the CPU socket completely unnecessary. The hard drive can also be immersed. This would also dampen drive noise, as well as provide additional cooling.

The only downside is the price: 11 lb (5 kg) of this fluid costs about $70 (I've e-mailed the company rep for North America for this material and asked for pricing information and where one can buy this fantastic sounding stuff - maybe we can drop this information into the story later when it's made available to me?). That's a lot more than you'd pay for cooking oil! But if you were to make the enclosure smaller, as the improved heat transfer characteristics of this fluid readily permit, you wouldn't necessarily need eight gallons, either.

With best wishes,
Ferdinand Wimmer

Use Silicon Oil

Too bad that you didn't make your first try with silicon oil or something similar. Then you could have let the system run at a heavy load for at least a couple of weeks. I hope you're inclined to try something along those lines in the future.

It's clear that extended use of salad oil would quickly lead to gummed-up components and a stinky, rancid mess reminiscent of rotting fish. I also believe that in any case use of silicon oil would lead to a longer system lifetime.

I'm also curious about what would happen if the oil should penetrate between the individual silicon and metal layers on the circuit boards, insofar as that is possible.

Your friend,
Josef Fischer

P.S.: You have my special respect for your attempts with distilled water!