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Set PWM Frequency on LM63 !?

Discussion in 'ATITool' started by MMos, Feb 23, 2005.

  1. MMos New Member

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    The problem: my Fan makes 'clicking' sounds.

    First thing that came into my mind: It's because the LM63 has digital Fan control (PWM).
    I ran some test to verify my thoughts.

    1. I unplugged the fan from the card and connected it, to my powersupply, using a pot.
    result : Fan doesn't generate any clicking sounds at all.

    2. I connected a "Papst" fan to the fan-connector on my ATI Card.
    result: Clicking sounds ! (Less then the stock cooler but still there).

    3. I built a filter (100uF+2x7Ohm+2x4.7uh) and put the filter between the ATI Fan-out and the Fan.
    result: much less clicking sounds but still there :(

    I took a look at the LM63 Datasheet and saw that it is possible to change it's PWM frequency.
    I downloaded National's Sensor Eval 1.1 but it couldn't connect to the ATI LM63 (wrong address?)

    I realy would like to change the PWM frequency on my LM63, but i dont know how to do it ;)
    Is it possible to connect Sensor Eval to the ATI LM63 ?
    Is it possible to built a "change PWM option" for ATI Tool ?

    I had a similar problem with a Intel-Motherboard before. But there i could change the PWM frequency with Speedfan . I changed the PWM frequency from ~10KHz to ~20Khz and that helped alot! What i found out , if the PWM freq. is to low there are much clicking sounds, if the PWM freq. is to high the Fan start to "sing / hum"

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