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

Extreme cooling

  1. Jun 16, 2008 #1
    Hello everybody,
    my question is: do you get an increase in speed/power/performance when you "freeze" computer components such as the CPU with LN2 or phase change cooling, getting to under -100º,-150º.
    Because as long as i'm aware CPU´s are made out of semiconductors and as temp lowers the resistivity on these rises. (but i don´t really know the effect of resistivity in performance)
    Or is it just a super cool way of making sure the components don´t overheat?

    Preferably from a physics point of view

  2. jcsd
  3. Jun 16, 2008 #2


    User Avatar

    Staff: Mentor

    The motherboard of a computer tells the processor exactly what speed to run at. Adding extra cooling allows it to run cooler, which allows you to tell the motherboard to run it faster.
  4. Jun 16, 2008 #3
    Can´t this "mobo telling CPU" be overridden? Cause as far as i know, the mobo knows what temp the cpu is at through a sensor, and this sensor could be tricked, couldn´t it?
  5. Jun 16, 2008 #4


    User Avatar
    Science Advisor
    Gold Member

    When "overclocking" a CPU (upping the operating frequency beyond manufacturer-set specs) it will tend to generate more heat. As a result, it is necessary to add more cooling power in order to keep the CPU within proper operating temperature. Liquid nitrogen (not normally used for residential applications AFAIK) and vapor phase-change cooling units are the upper extreme of CPU cooling and tend to allow for maximum overcloking potential.

    Overclocking Article on MaximumPC.com:
  6. Jun 16, 2008 #5


    User Avatar

    Staff: Mentor

    The motherboard generally doesn't dynamically adjust the speed of the processor as temperature varies. But most can be manually adjusted to whatever speed you want. No need to trick any sensors.
  7. Jun 16, 2008 #6
    I used to deal with overclocking a few years back.

    Basically you want to give the CPU a cool temperature so you can maximize the potential out of it. There's a certain limit when cooling the chip doesn't promote stability.

    In computer chips, the processor can get its proper cooling through air methods (which is what most computers nowadays have). However, cooling heat through heat-sinks doesn't usually get the job done when it comes to more aggressive overclocking.

    You would need to use more effective methods such as using a water-cooling rig, peltiers, phase-change, etc.

    The point is, it keeps the processor cool enough to keep it stable at high speeds.

    Being able to modify the speed is dependent on the motherboard. Again, in general they do not dynamically alter the speed as a function of temperature. This usually only occur in the more recent CPUs that slow down as temperature increases as a safety method to keep you from frying your chip (Pentium 4s did this, and you basically recognize a lag in your computer when it's happening). However, motherboards that are targeted towards enthusiasts usually have a feature to modify the front side bus speed, the FSB multiplier, as well as the voltages.

    As you can see, you don't necessarily need a cooling system to be able to tweak your CPU, you just need a motherboard that permits you to.
  8. Jun 16, 2008 #7
    Thank you guys for all your answers!

    But I still have one question:
    which would be the difference between having your ultra-high-extremely overclocked CPU stable down at -150º or at 25º?
  9. Jun 16, 2008 #8
    You have more space to work with (varies between processors) in terms of overclocking.

    Some chips will fail to work regardless of how low you bring the temperature.

    However, depending on the CPU, there could be a lot of bus-speed to extract from the CPU being overclocked when running the CPU @ 25 degrees celcius and 0 degrees celcius (or even lower with peltiers or phase change).

    Again it depends on the CPU. Some overclock real well, but some are already clocked to their maxes, so they might become unstable just by messing with the bus-speeds even a little bit.
  10. Jun 22, 2008 #9
    overclocking also depends on the RAM and the mobo. I think that keeping your PC cooler than it needs won't give anything extra. It may prolong its life but I don't think you get better performance or something, just keep it cool at a good temp.
  11. Jun 22, 2008 #10
    That is true as well.

    Depending on the FSB however, you will need components that can function under those speeds.

    That is something I also neglected.

    RAM is extremely important because if you want to overclock (extremely), you need to have fast RAM that can handle the bus speeds. If you're providing too much FSB for slow RAM, then you will have an extremely unstable system.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook