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This is probably a stupid question, but one that has been nagging at my mind for a while.

I have seen a number of references online to using an oil-bath as effective server cooling. In general, the idea is to submerge the motherboard and associated hardware in a bath of light oil (sunflower, olive, etc) and the oil will effectively absorb heat from the equipment and dissipate it quickly. The sites typically include video/images of this process in action but the skeptic in me questions the validity of these claims.

I know that light cooking oils are supposed to have an extremely low electrical conductivity, but it still seems to me that, with component pins and etched pathways running fractions of millimeters apart on the board, any fluid still runs a high chance of creating short circuits.

So my question is: Is this actually a viable cooling option in computing, or is this an elaborate e-ploy to dupe the unsuspecting into frying (no pun intended) their equipment in a warranty-voiding manner?

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migrated from serverfault.com Nov 9 '09 at 17:18

This question came from our site for professional system and network administrators.

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This isn't sysadmin related. No serious sysadmin is going to "bathe a server in oil". In terms of product development, liquid cooling of computers is nothing new. Old Cray "Supercomputers" used liquid cooling, as have IBM mainframe computers. You're not going to plunge a modern-day rackmount server into a bath of oil and have positive outcomes with respect to warranty and maintainability. –  Evan Anderson Nov 9 '09 at 16:57
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If you bread it first, it might be tasty. –  chris Nov 9 '09 at 17:07
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dude, at some state fairs they'll deep fry anything –  quack quixote Nov 9 '09 at 17:31
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Thanks for all the great responses. Much more than the 'yes or no' I was expecting so thanks for the really good details! –  Mike Clark Nov 9 '09 at 18:18
    
Check out episode 93 of SYSTM here –  straussie Nov 9 '09 at 21:01

4 Answers 4

up vote 7 down vote accepted

Points speaking against oil cooling in a professional setting:

You may have to review the fire safety regulations. Having a few dozen liters of oil in your server room will add significantly to the fire load. All server hardware is certified for fire protection, in the sense it will not put other stuff on fire. An 800 Watt power supply will make a nice fryer if something goes bad.

Almost all cooking oils get smelly with age. Then you have to recycle the oil. That´s work, which means cost. Nevermind cleaning up after you each time you touch the damn thing. Let alone plugging in a new mouse.

Speed of repair if something goes wrong. Granted, almost always the moving parts break. But then you are adding a whole lot of new variables into the equation. Degradation of oil -> oxidation -> contacts. Effect on parts? Will the plastics change? The Elkos? The layers of the PCBs?

Good oils creep. Into the cables. And along them. Capillarity is your enemy! And god forbid one of the cables makes a bend and hangs down... drip drip.

How do you go about the parts that break most of the time, disks? They´re outside. So you need a rack for them. And cooling. And power. Soooo... if you are going to have a rack and cooling anyway, why go through the hassle with the tank?

No Aquarium. I would see the point if you could do it with water and have a goldfish or two in there. A server with fish would be seriously cool.

It certainly is fun to make at home. But to make a solid system at work? I´m not so sure.

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It works, and at least one company sells PCs pre-built to run fully submerged in oil for cooling. However, in all cases it is more complicated and adds additional risks compared to air cooling. To start with, you have to factor in the significant additional weight, not only in whatever structure is going to hold or support the equipment but also when moving things around. The oil has to be circulated and filtered and replenished, requiring more equipment, which must itself be maintained. There is the possibility of residue formation. If you're using vegetable oils, there might be bacterial growth. It's a lot of work to consider.

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The board is usually coated in sealant anyway, except at the pins. Oil really does have a low conductivity, and metal ions don't readily end up in solution in it (which is what makes water conductive - pure water is unconductive but doesn't stay pure for long easily).

It does work, but don't submerge hard drives as they usually have an air breathing hole.

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In Theory Oil Cooling is entirely feasible. The low number of Free Ions in oil make electrical conductivity highly unlikley. However as a practicle application it leaves alot to be desired.

  • Devices with moving parts, such as hard disk would need to be sealed or they will allow in oil, which will prevent the moving parts from working.
  • It increases the weight of the server significantly, which may prevent it being held in a rack.
  • Any servicing requires the server to be drained of oil and refilled when completed.
  • Any leak will be messy, and if unnoticed, lead to quick overheating of the server.

I'm not sure what your referring to as an elaborate ploy to void your warranty. No server manufacturer is secretly trying to get you to fill your server with water, and it should be obvious to anyone that doing so will void your warranty.

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I reference the "void your warranty" because I hadn't seen manufacturers that offered them before. The only ones I had seen previously were the '7eet 4@xors' trying to over clock their HP from Best Buy who tend to be fishy in their claims. –  Mike Clark Nov 9 '09 at 18:17

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