Advice on CPU fan weight - A7N8X-E

Discussion in 'Asus' started by KWW, May 18, 2004.

  1. KWW

    KWW Guest

    I was getting ready to put a really good fan on my son's A7N8X-E, a
    Thermaltake Silent Boost A1889-01. I had tried it on another board and, vs
    the stock AMD cooling fan (Retail box) it cut about 20C off the temperature
    (OK, I also used Arctic Silver with it... vs the stupid tape on the stock
    fan...).

    The fins are all copper... runs quietly... Anyway, the bummer is, on the
    A7N8X I see that there are holes to fasten down the CPU cooling fans that
    some with some of the heat sinks I looked at. Also, it doesn't look like
    the 462 CPU socket is fastened down to the mobo in any extra special way...
    so I wonder if this heatsink is going to be too heavy over the long haul...
    what with vibration and all. I like the way it is quiet, and the heat
    transfer characteristics of the all copper heat sink are attractive.

    Anybody have thoughts/experience/suggestions? I would prefer a fan that did
    now howl. I also want to keep the chip cool! If the case were sitting on
    its side so that CPU would be flat, that would be one thing, but this case,
    as with most of them these days, sits upright.

    I do not plan to overclock the system.

    TIA!
    --
    KWW


    ASUS A7N8X-E Rev. 1.01
    AMD XP+ 2600 (333 FSB)
    512 Megs DDR 3200 (yeah... it cost about the same at the time, why not?)
    Chaintech GeForce FX5200 DDR 256MB (128 bit datapath)
    120 Gb WD EIDE ATA 133
    Sony CR/RW
    Antec case (either will Run an Antec 300W P/S or a 420W Turbolink CWT 420
    P/S)
     
    KWW, May 18, 2004
    #1
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  2. KWW

    Canus_Lupis Guest

    It is true that copper will rip the heat out of the cpu in a hurry but the
    sad fact remains as to how you get the heat out of the copper because copper
    is a bugger to cool.
    Aluminium still can`t be beat as far as that goes.
    You will have to do your homework with the weight factor too. I understand
    you have a hell of a job booting a computer when the cpu socket and cooler
    are laying at the bottom of your case.
     
    Canus_Lupis, May 18, 2004
    #2
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  3. KWW

    Paul Guest

    On the Zalman web page for the 7000a, it says:

    "Specified maximum weight for a cooler is 450g for the Intel
    Pentium 4 and the AMD Athlon 64, and 300g for the AMD
    Socket 462 CPU. Special care should be taken when moving a
        computer equipped with a cooler exceeding the weight guideline."

    People do use heatsinks which weight more than those limits, but
    obviously care must be taken when moving or bumping the equipment.

    There is also a spec (somewhere) for how much normal force can
    be safely applied to the socket or to the top of the processor
    chip (whether it has a heat spreader or not). The normal force
    is the force into the board, applied by the clamping mechanism,
    and the Intel retail solution must have taken first prize for
    applying the most force. The normal force maintains contact
    between the heatsink and the processor, under shock and vibration.
    Generally, as a user, you don't have a say in that parameter.

    As for how to shop for a heatsink - you can have a light/noisy/hot
    solution, or a heavy/quiet/cool solution. Heatsinks which use the
    screw holes aren't very popular, because the manufacturers got
    the impression that people didn't want to remove the motherboard,
    to remove the heatsink. For a person constantly pulling the processor,
    to try different ones, I guess you could see that point.

    Swifttech (swiftnets.com) used to have some heatsinks that used bolts
    to hold them down. There was a claim, that a computer equipped with
    a bolted heatsink was dropped from a second story window, and on
    landing, the heatsink was still in place (although the rest of
    the computer case was destroyed). So, using the bolts is definitely
    a worthy concept, it is just the convenience of top side clamps
    is more popular.

    Bolt on solution, now discontinued I think. Might be worth looking
    for, if you want something like this.
    http://www.swiftnets.com/products/MCX462+ INSTRUCTIONS.pdf

    This one uses the socket tabs.
    http://www.swiftnets.com/products/MCX462-V-installation-guide.pdf

    (All of their installation guides)
    http://www.swiftnets.com/installation.htm

    The downside of the Swifttech pin fin concept, is when you
    use "roughening" as a method of increasing the surface area
    of the heatsink, you pay a price in terms of noise. The turbulence
    and arrestance of the air path increases cooling efficiency and
    noise at the same time.

    A second concept, is the Zalman 7000 (either the AlCu or the
    pure copper one). It uses sheer size, and plenty of fins, to
    get a large surface area, with low resistance to air flow.

    http://www.zalman.co.kr/eng/product/view.asp?idx=54&code=005009

    This uses a lamination of plates, arranged as fins. Where the
    plates clamp together, forms a chunk of metal for the core. A
    fan, without noisy housing, provides the cooling air. Thermal
    resistance is around 0.22C/W, which is pretty good. It can be
    run at full speed without being audible. The downside of this
    solution, is its size. As I said above, this one is in the
    heavy/quiet/cool camp. Even the AlCu model is still over the
    allowed weight for a heatsink, but as long as you uninstall
    it before moving the computer, all will be well. If your computer
    was going to be a LAN party machine, stick with a bolt-on style
    solution, for peace of mind.

    Another issue, is the sheer physical dimensions of the thing.
    It has a radius of 55mm, measured from the center of the die.
    The PSU cannot be butted against the edge of your motherboard,
    if using one of these. To figure out the clearance required,
    drag a picture of your motherboard into Photoshop. The array
    of pins has outer dimensions of 1.8 inches, leaving 0.05 inches
    between rows. You can use those dimensions to estimate where
    55mm or 2.17" radius can reach. (2.17 - 0.9 = 1.27 inches, from
    the last row of pins, to the PSU.) The arrangement of PSU and
    motherboard must be such, that a small gap exists between them.
    I estimate about 0.35" minimum or so on your board.

    The Thermaltake has a thermal resistance of 0.5C/W. This means,
    if the processor dissipates 60W, the processor die will be 30C
    above the case air temperature. If that was 25C, then the
    die will be at 55C or so. The Thermaltake also doesn't have
    a weight specified, and is an all copper product.

    (You should take some of these thermal resistance ratings or
    graphs with a grain of salt, because some I have seen in print,
    are just ridiculously good.)

    HTH,
    Paul
     
    Paul, May 18, 2004
    #3
  4. KWW

    KWW Guest

    Thanks! I could not find the kind of info you came up with.... very useful!
     
    KWW, May 18, 2004
    #4
  5. KWW

    Nero Guest

    Use one on my XP2800.............................
    No problems at all.
    Motherboard is a A7N8X dlx.
     
    Nero, May 18, 2004
    #5
  6. I've got one of the Zalman 7000AlCu on an Asus A7v. It is a very
    quiet heatsink in the low speed mode, yet cools more than the factory
    heatsink with its noisy fan.
    Not only is there a weight problem, but the Zalman mounting
    arrangements are pretty grotty. The four holes around the CPU on my
    A7V are almost the same size as the cardboard washers they give you to
    put on both sides of the hole. The screws and washers almost pull
    through the board. They really should include some shouldered plastic
    washers that are of the right size for the motherboard holes.

    I've noticed is that Asus didn't do such a good job of selecting an
    appropriate CPU thermal sensor on my A7V. It clearly doesn't match
    the calibration curves in the associated IC that is reporting the
    temperature. The CPU temperature (even within seconds of being turned
    on after a long cool-down) shows "40 C" in the bios. The temperature
    after hard running for 10 minutes shows "54 C". As best as I can
    determine with my dandy Fluke temperature probe is that "54 C
    Asus-thermal-units" corresponds to around 40-degrees Celsius.
    Touching the heatsink hear the base confirms that it feels roughly
    "body temperature".

    I was very concerned about the possibility of the heatsink not having
    been making good contact. Pulling off the heatsink showed that the
    heatsink paste had been squeezed uniformly. It wasn't a case of the
    heatsink not seating deeply enough with insufficient pressure. I was
    still worried about the possibility of a trapped air bubble so I wiped
    off the grease and re-applied it a second time and tested again. The
    results were the same.

    I'm now leaning towards the conclusion that one can't trust the
    calibration of the ASUS. One needs to use a real temperature probe to
    convert from Asus temperature units to degrees C or F. Folks that
    think they are running hot should at least make sure that the heatsink
    really feels hot near the base.

    <include standard disclaimer for not sticking body parts into rotating
    cooling elements>

    -wolfgang
     
    Wolfgang S. Rupprecht, May 18, 2004
    #6
  7. KWW

    KWW Guest

    Thanks... now I just have to find a temperature probe that will work in this
    application.
     
    KWW, May 18, 2004
    #7
  8. I hope there isn't any problem with it, because I put that
    very same cooler on my A7N8X-E Dlx a week ago. :)

    Kind regards.
     
    Jose M. Arnesto, May 25, 2004
    #8
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