Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Heat conductivity in computers

  1. Jul 5, 2009 #1
    Hi, I hope this is the right forum.

    I'm doing a school project on how to improve heat dissipation in heat sinks (water primarily) in computers.
    I've realized that I've taken a larger bite than I can chew, but my teacher wouldn't let me change so, I'll guess I'm stuck with making an honest attempt hehe.

    I've looked around and there are of course a few things to consider. The obvious one being costs. Theoretically they could use all copper, but it's about three times the cost of aluminum which is generally known to be the next best thing when it comes to heat conductivity, although silver is better, it's also heavier and more expensive.

    What I'd want is something relatively cheap with great heat conductivity that will quickly dissipate heat, while still being light.

    If you could give me a few example on alloys (I'm guessing it has too be an alloy?)
    that will give you this. Manufacturing costs are obviously unknown to me, so I can't really speak for that. One alloy I've been eyeballing is Beralcast, have anyone of you ever heard of this?

    Thank you!

    / Patrik
     
  2. jcsd
  3. Jul 5, 2009 #2

    negitron

    User Avatar
    Science Advisor

    Well, the absolute king of thermal conductivity--and by a wide margin--is diamond. However, I imagine if copper is stretching your budget, diamond is out of the question entirely.

    Also, there's a factor you're overlooking which is far more important to heat dissipation than mere thermal conductivity and that's surface area (what do you think all the fins are for?)
     
  4. Jul 5, 2009 #3
    Yes, but I was thinking of water cooling blocks primarily now, maybe i was was vague.
    Anyway, yes diamond is a bit expensive ^^ Copper costs three times as much as aluminum.
    That's where this aluminum alloy came into the picture that i mentioned earlier. If the costs are lower than copper, and still is lower weight and have better thermal conductivity than both copper and aluminum wouldn't that be a given choice? Making a fan operated heat sink would of course require fins, but I'm strictly speaking of changing the actual composition of the heat sink itself, not how its made.
     
  5. Jul 5, 2009 #4

    negitron

    User Avatar
    Science Advisor

    For water cooling, you're probably better off increasing the water flow rate than anything else. For water cooling, you don't need a big mass of metal because it's the water that is your thermal transfer medium, rather than the metal composing the heatsink. For a water-cooled system you're better off with less metal mass, actually.
     
  6. Jul 5, 2009 #5
    You can use the aluminium contact but to better remove the heat you can use under-pressured water. Under-pressured water boils at lower temperatures so the heat removal is not due to the water heat capacity but due to the heat spent for vaporising. It is much better than just to heat the water.

    Under-pressured water is a water in a sealed volume with some empty sub-volume (no gas, only water vapour of low pressure).
     
  7. Jul 5, 2009 #6
    OK, I follow.. But in order to get the water running INTO the block to be cold enough under the increased water pressure you'd need fans that can push more air.. So.. It's either faster spinning fans or bigger fans on the radiator. You can't really have an unlimited size on the fans, unless you have a stationary (external) radiator, which is very cumbersome. And faster.. Well that about spoils the sound reduction..

    Let's review the possibilities of normal fan "powered" heat sinks then. Copper is to my knowledge the "best". Not necessarily best in terms of thermal conduction, but after looking at the pro's and con's. Are there any alloys that could make a better job than copper? I'm not sure that I mentioned it in my opening post but
    http://www.matweb.com/search/datashe...b83c0e985fe630

    There are two more variations of this (see near bottom left of the page)

    Now, I'm not a physicist so those numbers don't tell me much. Neither have I ever been good with calculations. I'm more of a linguist really..
     
    Last edited: Jul 5, 2009
  8. Jul 5, 2009 #7

    negitron

    User Avatar
    Science Advisor

  9. Jul 5, 2009 #8
    Yes negitron, thats the one. I'll edit my own link as well.
     
  10. Jul 6, 2009 #9

    ideasrule

    User Avatar
    Homework Helper

    For a completely different idea, how about immersing the entire computer--motherboard, power supply, CPU and all--in an aquarium filled with mineral oil? It's been done by overclockers in an attempt to cool down their overclocked motherboards, but it apparently takes a lot of work to get good results (see http://news.zdnet.co.uk/hardware/0,1000000091,2078339,00.htm). If you can find a similar insulating liquid that conducts heat much better, that'll be great!
     
  11. Jul 6, 2009 #10
    Well you can get nearly 200 below (Celsius) with liquid nitrogen :)
    Though I don't see the practicality with either that nor submersing the entire computer in mineral oil ^^
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook