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Notebook Cooling Strategies

Posted by michael on from the lap-burns dept.

An Anonymous Coward writes "As components shrink, heat control becomes critical. Hitachi will sell water-pump cooling for notebooks while Sony has fancy, twin-fan ductwork in its new Vaio laptops. Meanwhile, a ceramics company that's testing a coating that's highly efficient in radiating heat away from processors and race car engines." We mentioned the water-cooled notebooks earlier.

3 of 163 comments (clear)

  1. My Dell C800 by peterdaly · · Score: 3, Insightful

    I have a Dell C800 (1ghz) laptop. When the fan comes on, people look over...when the second comes on, people dive for cover. (Well, maybe they are not really that loud) It would be nice if they could sync the RPM's a little better so it doesn't have the "whir" "whir" "whir" sound. That's the price I have to pay for a 1st gen gightz laptop.

    I've got some copper piping stuff going from my CPU to the fans, which supposedly has some super heat conductive stuff in it.

    -Pete

    --
    Soccer Goal Plans
  2. Possible Avenues by Effugas · · Score: 3, Insightful

    1) We're going to finally start seeing hard-drive free systems. RAM is actually cheap enough that one to two gigs, living off an independent power supply, should be price competitive with a ten gig hard drive. Though XP might need to be shaved down a bit to fit in such a small amount of space, the increased system speed and vastly decreased amount of moving parts should make a significant difference in both power consumption and heat generation(the two are arguably the same thing). On the flip side, repeatedly pulsing that much memory might actually drain more power than I'd guess, and battery life on the RAM might not extend past a few days. In this case, I could still see a microdrive + RAM combo, or even a system that flat out just ran off a 2gb microdrive.

    2) CPU heat will eventually be turned into a power source. Heh -- it's there, it's dependable, and if nothing else, it'll supplement primary power sources. I don't know how efficient electrical heat->power systems are -- I doubt Peltiers are going to work too well here, and we ain't sticking a turbine into a laptop (though Microfluidics just got much, much more interesting!). So this is the "five-to-ten years down the road" likelihood.

    3) I feel like sounding like an idiot for a second, so I'll put this out there just for someone else to discredit: What about mechanical compression? Imagine a spring on the side of a laptop that needed to be pushed in periodically, but would absorb heat by slowly expanding. It'd be annoying, but each time the spring was compressed, heat should be lost reasonably harmlessly to the user's musculature. I'm sure this doesn't work, but I'd be interested in knowing the history of why not.

    Yours Truly,

    Dan Kaminsky
    DoxPara Research
    http://www.doxpara.com

  3. Phase-change heat pipes by tbo · · Score: 3, Insightful
    are the way to go... I saw them advertised by an OEM a few years ago. Here's how they work:
    The heat pipe contains a liquid/gas that changes phase around the operational temperature of the device you wish to cool. At the hot end of the pipe, the liquid evaporates, sucking up the heat of vaporization. The vapor travels to cold end of the pipe, and condenses there, releasing heat. The inside of the pipe is specially-designed so as to use capilliary action to draw the liquid back to the hot end of the pipe. What all this does is give you a pipe that has an effective thermal conductivity many, many times better than a hunk of copper (which is already a damn good thermal conductor).
    Presumably, you use these pipes to move heat away from the CPU towards the outer chassis of the laptop.

    Looking inside my Apple PowerBook G4, I see things that look very much like pipes traveling away from the CPU to other areas of the laptop (areas which tend to get rather warm), and I assume these are the phase-change heat pipes I heard about a few years back. Whether Apple is the only company doing this, I don't know, but it is sure cool, pardon the pun. The fact that the G4 consumes less power is also a big help.

    I'm now going to go off on a tangent, mentioning various aspects of physics that are barely relevant, but pretty damn cool. First of all, a bunch of people have suggested using the heat as a power source. While you can use temperature gradients as a power source (think thermocouples), it's damn unlikely to be practical here (the power harnessed would be trivia).

    Second, I'd like to point out that heat dissipation is becoming an increasingly-important problem in CPU design. Although we're not there yet, there are theoretical limits on how efficient non-reversible computations can be, in a thermal sense. In other words, each time you manipulate a bit (to be really picky, each time you reset a bit), it must produce a certain amount of heat. This could be the hard limit that breaks Moore's Law for classical, non-reversible computers. The way around this is to use reversible gates (such as in quantum computing), which have no such minimum heat cost. For instance, the XOR gate can be replaced with the controlled-not (CNOT) gate, which is reversible. This would require a major reworking of how we build computers... But I digress... Suffice it to say, heat is a big problem, and it's only going to get worse.