CPU Cooling Fan Question

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

As the warmer weather approaches New England, the CPU fan has to work
harder.
I have a P5GDC De luxe running with a P4 3.2GHz 800 MHz FSB
I am using the Intel fan suppled with the CPU.
Although it does keep the CPU at reasonable temperatures, say 100 deg F,
the fan is really quite noisy and it is running at 4500 RPM at the moment.
The side of the PC case is removed for maximum ventilation.
Since I am a long way from dangerous CPU temperatures I would have
thought the fan would be running more slowly. I don't see a way to
schedule the system gain to trade CPU temperature for lower fan speed.

Also I note that the fan is running to push air into the heat sink,
rather than draw the air out. Is this correct? I thought most fans
acted to draw air out of the heatsink area and not blow it in. The way
it runs now ,clockwise rotation, is very noisy since the fan blades are
chopping the wakes from the support struts, thus making a siren noise.

So what is the received wisdom for the quietest and most effective
cooling system for the P4?

Thanks

Bruce
4 answers Last reply
More about cooling question
  1. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <BVy9e.22101$nt3.16549@trndny04>, bruce.s.murray@verizon.net wrote:

    > As the warmer weather approaches New England, the CPU fan has to work
    > harder.
    > I have a P5GDC De luxe running with a P4 3.2GHz 800 MHz FSB
    > I am using the Intel fan suppled with the CPU.
    > Although it does keep the CPU at reasonable temperatures, say 100 deg F,
    > the fan is really quite noisy and it is running at 4500 RPM at the moment.
    > The side of the PC case is removed for maximum ventilation.
    > Since I am a long way from dangerous CPU temperatures I would have
    > thought the fan would be running more slowly. I don't see a way to
    > schedule the system gain to trade CPU temperature for lower fan speed.
    >
    > Also I note that the fan is running to push air into the heat sink,
    > rather than draw the air out. Is this correct? I thought most fans
    > acted to draw air out of the heatsink area and not blow it in. The way
    > it runs now ,clockwise rotation, is very noisy since the fan blades are
    > chopping the wakes from the support struts, thus making a siren noise.
    >
    > So what is the received wisdom for the quietest and most effective
    > cooling system for the P4?
    >
    > Thanks
    >
    > Bruce

    XP-120 0.18C/W with inaudible fan
    XP-90 0.18C/W with inaudible fan
    Zalman 7000B 0.22C/W with fan at full speed (reasonably quiet)
    Zalman 7700 0.21C/W with fan at full speed (reasonably quiet)

    This article says the Intel S478 retail HSF is 0.33C/W
    http://www.silentpcreview.com/article138-page1.html

    http://www.overclockers.com/articles1094/ (Review of the XP-90)
    http://www.overclockers.com/articles1043/ (Review of the XP-120)
    http://www.silentpcreview.com/article194-page1.html (XP-90 review)
    http://www.thermalright.com/a_page/main_product_accessories.htm#acc_775
    http://www.thermalright.com/a_page/main_support_installation_lga775.htm

    http://www.zalman.co.kr/eng/product/view.asp?idx=142&code=005009
    ZM-CS1 Adapter for Zalman 7000x, for use with LGA775:
    http://www2.newegg.com/Product/Product.asp?Item=N82E16835118219
    http://www.zalman.co.kr/eng/product/view.asp?idx=146&code=005009
    http://www.zalman.co.kr/product/cooler/7700-775MBlist_eng.htm

    These are large heatsinks, and some of them overhang the edge of
    the motherboard. As well as having to worry about clearance to
    DIMMs, Northbridge heatsink, and capacitors, some space is
    typically needed between the top edge of the motherboard and
    the PSU.

    On the Thermalright, you will need to purchase a separate fan.
    (Which is a nuisance, finding a fan with a tachometer output
    signal, for monitoring by the CPU_FAN header.)

    The above products are not too tall, so there is not a lot of
    torque on the socket when the heatsink is in place. You can avoid
    excess weight on the Zalman heatsinks, by using the AlCu version.

    I don't recomment tower coolers, due to the tendency for them to
    pull on the motherboard, when the computer is upright. It is not
    just the weight which is an issue, it is what happens if the computer
    case receives a shock, and how the tower will behave then.
    Generally, the heavier the assembly, or the more susceptable
    to shock, then the higher the clamping pressure needed to keep
    the heatsink on the socket.

    There are a number of other heatsinks out there, some of which
    will not have an overhang issue, but the noise and performance
    may not be much better than the Intel retail product.

    (review list)
    http://www.overclockers.com/topiclist/index15.asp
    (recommended product list)
    http://www.silentpcreview.com/article30-page1.html
    (review list)
    http://www.silentpcreview.com/article_index.php#cooling

    HTH,
    Paul
  2. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    Paul wrote:
    > In article <BVy9e.22101$nt3.16549@trndny04>, bruce.s.murray@verizon.net wrote:
    >
    >
    >>As the warmer weather approaches New England, the CPU fan has to work
    >>harder.
    >>I have a P5GDC De luxe running with a P4 3.2GHz 800 MHz FSB
    >>I am using the Intel fan suppled with the CPU.
    >>Although it does keep the CPU at reasonable temperatures, say 100 deg F,
    >>the fan is really quite noisy and it is running at 4500 RPM at the moment.
    >>The side of the PC case is removed for maximum ventilation.
    >>Since I am a long way from dangerous CPU temperatures I would have
    >>thought the fan would be running more slowly. I don't see a way to
    >>schedule the system gain to trade CPU temperature for lower fan speed.
    >>
    >>Also I note that the fan is running to push air into the heat sink,
    >>rather than draw the air out. Is this correct? I thought most fans
    >>acted to draw air out of the heatsink area and not blow it in. The way
    >>it runs now ,clockwise rotation, is very noisy since the fan blades are
    >>chopping the wakes from the support struts, thus making a siren noise.
    >>
    >>So what is the received wisdom for the quietest and most effective
    >>cooling system for the P4?
    >>
    >>Thanks
    >>
    >>Bruce
    >
    >
    > XP-120 0.18C/W with inaudible fan
    > XP-90 0.18C/W with inaudible fan
    > Zalman 7000B 0.22C/W with fan at full speed (reasonably quiet)
    > Zalman 7700 0.21C/W with fan at full speed (reasonably quiet)
    >
    > This article says the Intel S478 retail HSF is 0.33C/W
    > http://www.silentpcreview.com/article138-page1.html
    >
    > http://www.overclockers.com/articles1094/ (Review of the XP-90)
    > http://www.overclockers.com/articles1043/ (Review of the XP-120)
    > http://www.silentpcreview.com/article194-page1.html (XP-90 review)
    > http://www.thermalright.com/a_page/main_product_accessories.htm#acc_775
    > http://www.thermalright.com/a_page/main_support_installation_lga775.htm
    >
    > http://www.zalman.co.kr/eng/product/view.asp?idx=142&code=005009
    > ZM-CS1 Adapter for Zalman 7000x, for use with LGA775:
    > http://www2.newegg.com/Product/Product.asp?Item=N82E16835118219
    > http://www.zalman.co.kr/eng/product/view.asp?idx=146&code=005009
    > http://www.zalman.co.kr/product/cooler/7700-775MBlist_eng.htm
    >
    > These are large heatsinks, and some of them overhang the edge of
    > the motherboard. As well as having to worry about clearance to
    > DIMMs, Northbridge heatsink, and capacitors, some space is
    > typically needed between the top edge of the motherboard and
    > the PSU.
    >
    > On the Thermalright, you will need to purchase a separate fan.
    > (Which is a nuisance, finding a fan with a tachometer output
    > signal, for monitoring by the CPU_FAN header.)
    >
    > The above products are not too tall, so there is not a lot of
    > torque on the socket when the heatsink is in place. You can avoid
    > excess weight on the Zalman heatsinks, by using the AlCu version.
    >
    > I don't recomment tower coolers, due to the tendency for them to
    > pull on the motherboard, when the computer is upright. It is not
    > just the weight which is an issue, it is what happens if the computer
    > case receives a shock, and how the tower will behave then.
    > Generally, the heavier the assembly, or the more susceptable
    > to shock, then the higher the clamping pressure needed to keep
    > the heatsink on the socket.
    >
    > There are a number of other heatsinks out there, some of which
    > will not have an overhang issue, but the noise and performance
    > may not be much better than the Intel retail product.
    >
    > (review list)
    > http://www.overclockers.com/topiclist/index15.asp
    > (recommended product list)
    > http://www.silentpcreview.com/article30-page1.html
    > (review list)
    > http://www.silentpcreview.com/article_index.php#cooling
    >
    > HTH,
    > Paul
    Paul

    Thanks once again for your deep insights into these systems. I am sure
    other list members will benefit from your summary.
    As is so often the case I was able to improve my situation by reading
    the manual!
    I did not have the BIOS set up the best way. I had disabled the Q Fan
    Control. Now I have it enabled and also have the Fan Mode in PWM and
    the fan ratio set to Auto.
    It's pretty quiet now and the CPU temperature is reasonable.
    I had no idea about the PWM fan control system by Intel and even after
    spending a little time on the website, I am still not completely clear
    on the logic being used.
    Is there a "plain man's guide to the Intel Fan PWM control" that you
    know of?


    Thanks

    Bruce
  3. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    On Wed, 20 Apr 2005 23:04:01 -0400, nospam@needed.com (Paul) wrote:

    >In article <BVy9e.22101$nt3.16549@trndny04>, bruce.s.murray@verizon.net wrote:
    >
    >> As the warmer weather approaches New England, the CPU fan has to work
    >> harder.
    >> I have a P5GDC De luxe running with a P4 3.2GHz 800 MHz FSB
    >> I am using the Intel fan suppled with the CPU.
    >> Although it does keep the CPU at reasonable temperatures, say 100 deg F,
    >> the fan is really quite noisy and it is running at 4500 RPM at the moment.
    >> The side of the PC case is removed for maximum ventilation.
    >> Since I am a long way from dangerous CPU temperatures I would have
    >> thought the fan would be running more slowly. I don't see a way to
    >> schedule the system gain to trade CPU temperature for lower fan speed.
    >>
    >> Also I note that the fan is running to push air into the heat sink,
    >> rather than draw the air out. Is this correct? I thought most fans
    >> acted to draw air out of the heatsink area and not blow it in. The way
    >> it runs now ,clockwise rotation, is very noisy since the fan blades are
    >> chopping the wakes from the support struts, thus making a siren noise.
    >>
    >> So what is the received wisdom for the quietest and most effective
    >> cooling system for the P4?
    >>
    >> Thanks
    >>
    >> Bruce
    >
    >XP-120 0.18C/W with inaudible fan
    >XP-90 0.18C/W with inaudible fan
    >Zalman 7000B 0.22C/W with fan at full speed (reasonably quiet)
    >Zalman 7700 0.21C/W with fan at full speed (reasonably quiet)
    >
    >This article says the Intel S478 retail HSF is 0.33C/W
    >http://www.silentpcreview.com/article138-page1.html
    >
    >http://www.overclockers.com/articles1094/ (Review of the XP-90)
    >http://www.overclockers.com/articles1043/ (Review of the XP-120)
    >http://www.silentpcreview.com/article194-page1.html (XP-90 review)
    >http://www.thermalright.com/a_page/main_product_accessories.htm#acc_775
    >http://www.thermalright.com/a_page/main_support_installation_lga775.htm
    >
    >http://www.zalman.co.kr/eng/product/view.asp?idx=142&code=005009
    >ZM-CS1 Adapter for Zalman 7000x, for use with LGA775:
    >http://www2.newegg.com/Product/Product.asp?Item=N82E16835118219
    >http://www.zalman.co.kr/eng/product/view.asp?idx=146&code=005009
    >http://www.zalman.co.kr/product/cooler/7700-775MBlist_eng.htm
    >
    >These are large heatsinks, and some of them overhang the edge of
    >the motherboard. As well as having to worry about clearance to
    >DIMMs, Northbridge heatsink, and capacitors, some space is
    >typically needed between the top edge of the motherboard and
    >the PSU.
    >
    >On the Thermalright, you will need to purchase a separate fan.
    >(Which is a nuisance, finding a fan with a tachometer output
    >signal, for monitoring by the CPU_FAN header.)
    Quite true. I started a thread on this a few weeks ago, but I didn't
    get many suggestions. I'd like to use a Panaflo fan, but the 120mm
    models have no tach output. I'm still looking for suggestions about
    the best and most silent 120mm fans for the XP120 that DO have the
    tach output. Some suggested that I'd not need the RPM-monitoring
    function on the CPU fan, and I'm sure that's true, but I'd just like
    to be able to do it. Any suggestions from users??
    >
    >The above products are not too tall, so there is not a lot of
    >torque on the socket when the heatsink is in place. You can avoid
    >excess weight on the Zalman heatsinks, by using the AlCu version.
    >
    >I don't recomment tower coolers

    I'm not sure what you mean by "tower coolers." I guess you're saying
    that the XP120 is not a "tower cooler" when you state that the "above
    products are not too tall." Am I inferring correctly? If so, what's
    an example of a tower cooler?

    >due to the tendency for them to
    >pull on the motherboard, when the computer is upright. It is not
    >just the weight which is an issue, it is what happens if the computer
    >case receives a shock, and how the tower will behave then.
    >Generally, the heavier the assembly, or the more susceptable
    >to shock, then the higher the clamping pressure needed to keep
    >the heatsink on the socket.
    >
    >There are a number of other heatsinks out there, some of which
    >will not have an overhang issue, but the noise and performance
    >may not be much better than the Intel retail product.
    >
    >(review list)
    >http://www.overclockers.com/topiclist/index15.asp
    >(recommended product list)
    >http://www.silentpcreview.com/article30-page1.html
    >(review list)
    >http://www.silentpcreview.com/article_index.php#cooling
    >
    >HTH,
    > Paul

    Ron
  4. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <et6ae.13$WX.7@trndny01>, bruce.s.murray@verizon.net wrote:

    > Paul
    >
    > Thanks once again for your deep insights into these systems. I am sure
    > other list members will benefit from your summary.
    > As is so often the case I was able to improve my situation by reading
    > the manual!
    > I did not have the BIOS set up the best way. I had disabled the Q Fan
    > Control. Now I have it enabled and also have the Fan Mode in PWM and
    > the fan ratio set to Auto.
    > It's pretty quiet now and the CPU temperature is reasonable.
    > I had no idea about the PWM fan control system by Intel and even after
    > spending a little time on the website, I am still not completely clear
    > on the logic being used.
    > Is there a "plain man's guide to the Intel Fan PWM control" that you
    > know of?
    >
    >
    > Thanks
    >
    > Bruce

    The Intel fan has four pins. +12V and GND are power for the
    fan. The Tachometer signal is used by the motherboard, to
    monitor whether the fan is spinning or not. Those are
    standard on both the old three pin and new four pin fan
    headers.

    First, a little background. You've likely noticed a whole
    raft of products that adjust the fan speed. Basically they
    use two methods for adjusting the fan speed. Both methods
    reduce the voltage, but the implementation affects how
    efficient the schemes are.

    One kind of scheme, puts a resistance in the +12V line.
    This drops some voltage, so that less voltage is made
    available at the fan terminals. The only problem with a
    scheme like this, is the device doing the "resisting"
    gets hot. It dissipates power equivalent to the dropped
    voltage times the current flow. For example, if the
    resisting device drops the voltage from 12V to 7V, and
    the fan draws 0.1 amp, the power wasted in the resisting
    device is 0.5 watts. This is generally an issue if the
    resisting device doesn't have a nice flow of cooling air
    over it or wasn't given a heatsink of some sort.

    The second scheme is called Pulse Width Modulation. The
    control signal in this case, is at a constant frequency,
    and the frequency is likely a lot higher than the fan
    speed. The pulse is repetitive, and only the width of
    the pulse changes. It is obvious, if the pulse is 12V
    high, and has 100% duty cycle, that the resulting voltage
    can only be exactly 12V. If the duty cycle is less than
    100%, and the pulse is filtered with a capacitor, then
    the time averaged voltage developed across the capacitor
    is proportional to the pulse width. The voltage on the
    capacitor will have some ripple on it, and sometimes the
    result is a little extra noise coming from the fan hub.

    The beauty of PWM, is that the power switching device
    making the +12V square wave, is either completely
    turned on (saturated) or completely turned off (open).
    In either state, it dissipates virtually zero power
    (since in one case, the voltage drop is zero, and in the
    other case, the current flow is zero.) That means, the
    PWM transistor can be soldered to the motherboard, without
    worrying about cooling.

    OK. Now we return to the Intel fan header. The +12V line
    feeding the fan, can be fed by either of the solutions
    mentioned above. If a motherboard chooses to only touch
    the standard three pins, then either kind of solution
    can be added to the motherboard (linear resisting device
    or PWM switching, feeding the +12V line to the fan).

    A motherboard can also offer to use the fourth pin on
    the Intel fan. This pin also uses the PWM method, only
    some of the electrical components are inside the fan
    hub. Why Intel thinks this is the "bees knees" is a
    good question. The fan will be a few more cents
    expensive than before, due to the PWM transistor and
    filter capacitor being inside the fan hub. The motherboard
    still has to generate a square wave, with a variable pulse
    width, as determined by the fan speed that the BIOS or some
    Windows driver/program decide. Effectively, the Intel
    solution is the same as the motherboard version of PWM,
    only the solution is distributed between the fan
    and the motherboard.

    So, what is the difference between using a motherboard-only
    PWM scheme, and the Intel in-the-fan-hub PWM scheme ?
    Should be no difference. If both the motherboard and
    the fan implement PWM for themselves, then there is
    unnecessary duplication of functionality. Maybe someone
    can explain why this is a good thing, 'cause I don't
    get it. The old way was getting the job done...

    I suppose if the motherboard designer sticks with the Intel
    provided solution, they don't need a PWM transistor and
    a capacitor, but if the user plugs in an after market
    three pin fan, then there would be no fan speed control
    available.

    As for where the PWM signal comes from, the hardware monitor
    circuitry usually has the fan control PWM signal generator
    inside it. So, if the motherboard is going to have a hardware
    monitor anyway, the ability to do PWM can come for "free".

    Paul
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