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Q & A: Can I cool a CPU with dry ice?

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Q:
Hi, I have a computer with an overclocked CPU, it gets pretty hot but i dont want to invest 100 bucks in watercooling. So.. Here’s my qeustion: Is it possible for me to cool my cpu using a block of dry ice?
- Mohammad
Herndon, VA
A:
Cooling your CPU with dry ice does not sound like a good idea. There are many problems associated with this technique.

1) Dry ice has to be bought, stored, and handled very carefully. It doesn't last all that long (it sublimates, boiling off carbon dioxide constantly). You can't touch it with your hands (wear extra-thick gloves, and keep water away!). You may be able to get some at ice-cream shops, but the cost may add up to more than $100 if you run your computer a lot like this.

2) You constantly have to add more dry ice -- it sublimates away all the time. Depending on the size of the chunk you put in your computer, you may have to replace it every few minutes. A 2.2 GHz Pentium 4 (a typical modern processor) dissipates 57 watts of thermal energy. The latent heat of dry ice is 590000 Joules per kilogram, meaning you'd go through the stuff at a rate of about a pound an hour. Overclocking only speeds this up. And it absorbs heat from the air and surroundings, not just the processor, so it disappears even faster.

3) In a humid environment, the dry ice will frost up. Water vapor will condense on the block of dry ice and make regular ice. When the dry ice sublimates, this stuff falls on your processor and motherboard, making it wet. Even just cooling off the components of the computer below the dew point will cause water to spontaneously condense on your computer parts. They may not work when wet (short circuits!), or the water may speed the corrosion of electrical contacts.

4) You need good thermal contact between your dry ice and the processor. Dry ice when it changes into a gas, makes a thin cushioning layer of escaping carbon dioxide around it. This acts as a thermal blanket, keeping more heat from traveling to the ice. You can push the dry ice against the CPU, but what will happen then is that you will get vibrations. Vibrations tend to shake electrical contacts loose.

5) Speaking of electrical contacts, cooling a portion of your computer down to very low temperatures and not others will create mechanical stresses in your computer parts (most likely in your processor). When stuff cools down, it shrinks, and when it heats up, it expands again. Cooling down only a part of your computer makes that part too small to fit nicely into the other parts. You may crack something or, more likely, just break some electrical contact somewhere. Small electrical components can be fragile!

6) You have to make sure not to run out of dry ice -- if you run empty, the processor will overheat very rapidly and stop working.

Water cooling is difficult -- you have to make sure there are no leaks and no vibrations introduced by pumps. It is (was) often used for large mainframe computers, but is not common on today's smaller units.

Our suggestion is to get a good heat sink and a fan. There is no limit to how much heat they can carry away -- air comes in for free, and the fan and heatsink are not that expensive (your computer probably already came with one, but you might want to get a better one). You may want to look at heatsink roundups on computer-related websites, but be forewarned about the quality of information you may find on the web. You can also slow down the processor again. Usually you can get more performance out of a computer by buying one later, as processors get cheaper and faster all the time anyway, and overclocking is just a really hard way to go about this.

-Jeff and Tom

(republished on 07/25/06)

Follow-Up #1: dry ice CPU cooling

Q:
I know this is an old question but using dry ice is very feasible and affordable for cooling CPUs. Information (older than this original post) can be found about how to do this in a sensible manner. Just google "dry ice cpu cooling" and you'll find a wealth of guides and techniques, including youtube videos, of how this is done.
- Tim (age 36)
Omaha, Nebraska, USA
A:
It's certainly possible, as you say. However, if you look at those videos etc., you can see it's not exactly easy. The set up is quite bulky, you need a lot of care to make sure you don't accidentally condense some water and have it drip on the circuit, and you get in big trouble quickly if the dry ice runs out while you're running. Some of the other issues that Jeff and Tom mentioned are not so crucial. A dry-ice acetone bath in a copper container can make good thermal contact, for example. I think Jeff and Tom were right, however, that this is an impractical technique for the vast majority of users.

Mike W.

(published on 06/26/11)

Follow-Up #2: cpu thermal cooling

Q:
A long time ago I had purchased what used to be referred to as a "thermal cooling blanket" that was positioned between the CPU and the heat sink. It really did feel very cold to the touch. I have searched high and low but cannot find it anywhere on the internet. Would you happen to know where I can find this devise again. It's description looking like a small square piece of linoleum. White on top and aluminum on the bottom. It really kept my CPU from ever cooking. It was a wonderful computer component!!!
- AC (age 45)
Los Angeles, CA, USA
A:
I'm not sure what that was. It might have just been a passive device intended to improve the thermal contact to the heat sink. If so, it sounds like overkill compared to high-quality thermal conductive grease. From the asymmetrical sides, it sounds as if it might have been an active Peltier heat-pump device. Did it have a couple of wires coming out that connected to a dc supply on the computer?

Mike W.

Unchecked post, Lee's in Paris.

(published on 11/28/11)

Follow-up on this answer.