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C-states & P-states cause PSU scratching noise (possible ground loop) 10.7.3

C-states P-states PSU noise ground loop EX58 i7 920 1366

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Hi all,

I Recently installed OSX 10.7.3. My MB is a Gigabyte EX58-UD4 for which I have the correct DSDT matched to my BIOS version. The DSDT enables C-states & P-states in my org.chameleon.boot.plist. Having these enabled is causing my PSU to make a scratching/wining noise which responds (gets worse) with mouse movement and application loading. (questionable ground loop)

I had the same problem in Win7 x64 which is on a separate HD, but disabling CPU EIST, Intel Turbo tech & C1E halt in the BIOS stopped the noise. The problem persists in OSX regardless of these changes. The only way I can stop the PSU from making these noises is to set P-states & C-states =No.

I'm told this could have an adverse effect on my CPU and I'm aware that the changes I have made to the plist are covering up a problem and not fixing it. I'd be hugely grateful if some of the more experienced builders could shed some light on this matter and or give me some instructions for diagnosis/cure.

My CPU idles at between 50-55c and under load climbs to 60-61c

Many thanks


Gigabyte EX58-UD4
Intel i7 2.66ghz quad (socket 1366)
12GB corsair RAM DDR3
ASUS nVidia 210 silent DDR3 1GB
Silver Power 500W PSU

Also tagged with one or more of these keywords: C-states, P-states, PSU noise, ground loop, EX58, i7 920, 1366

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