[mythtv-users] undervolting k8

Marius Schrecker marius at schrecker.org
Sun Dec 4 08:22:32 EST 2005


Hi,

As part of noise reduction I'm looking into gently undervolting my
athlon64 (3700+ san diego), and possibly setting a lower minimum
frequency. Powernow reports:$ dmesg |grep powernow
powernow-k8: Found 1 AMD Athlon 64 / Opteron processors (version 1.50.4)
powernow-k8:    0 : fid 0xe (2200 MHz), vid 0x6 (1400 mV)
powernow-k8:    1 : fid 0xc (2000 MHz), vid 0x8 (1350 mV)
powernow-k8:    2 : fid 0xa (1800 MHz), vid 0xa (1300 mV)
powernow-k8:    3 : fid 0x2 (1000 MHz), vid 0x12 (1100 mV)

This despite trying to reduce vcore in the bios from 1400mV to 1300.

What I want is some way to override the pst tables supplied by the bios.
I've seen some patches around, but none of them are aimed at higher 2.6
kernels, and I don't feel up to messing about here with things I don't
fully understand.

Does anyone know of a patch to 2.6.14 that would let me either hardcode my
preferred fid/vid  values, or, prefereably, manipulate them on the fly by
writing new values to /sys (I only see frequency values here, nothing to
do with vcore)?

Also, is it possible that this processor supports speeds as low as 800MHz?

Any pointers appreciated.

Cheers

Marius


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