"Mark" <markalroberts******.com> wrote in message
news:1165992463.103242.3700@80g2000cwy.googlegroup s.com...
> Hi
>
> I recently received my new Dell 640m with Core 2 Duo processor -
> lovely! Except I got an annoying high pitch noise - barely detectable,
> but annoying people with good hearing!
>
> So, looking on the forums, it seems people are reporting the same
> problem on various machines, and it seems to be related to the CPU and
> the frequency it runs at setting up some sort of resonance.
>
> The advice was to download RM CPU Clock utility (freeware, and very
> good!) and disable the "Enable Popup Mode" tickbox in the "Advanced CPU
> Settings" section.
>
> http://forum.tabletpcreview.com/showthread.php?t=3516
>
> I have tried this, and it really works! I can clearly detect the noise
> stopping/starting as I toggle this setting.
>
> I cannot immediately detect and down sides to this change of setting -
> the RM Clock readme states:
>
> "Enable Popup mode (auto C3/C4 to C2) - when this option is off, any
> bus master traffic causes the chipset to return from C3 or C4 state
> into C0 (working) state. When this option is on and the chipset
> observes a bus master request, it will take the system from C3 or C4
> state into C2 state and enable bus masters. This will let snoops and
> memory access occur. This setting is available only for ICH6-M and
> ICH7-M."
>
> I would really appreciate if anyone translate this into real-world
> performance/heat/battery life information for me :)
>

The CPU (and indeed other chips) draw their power in pulses rather than
continuously. As you note, this can sometimes create beat frequencies with
the power supply circuits (which also operate in pulses). The toggle you
made has altered the pulse pattern sufficiently to make the beat frequencies
inaudible. The heat output and battery life are unlikely to be detectably
affected. As for performance, it might be noticeable, if you compared it to
another popup mode enabled machine. Otherwise, you probably won't.