cpufreq for Xeon 5500 on linux

[priya_sehgalgmail_co]

Hello,
I have a Xeon 5500 with Linux installed on it and I wish to use the ondemand cpufreq governor to save power consumption of the server.
I had questions about the cpufreq software:
1. The cpufreq governor (on demand) shows /sys entries, one of which is from /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq. Does this file contain only the available frquencies or even the voltages ?
Does the cpufreq software allow to modify both voltage and frequency or only frequency.
I could not locate the available voltages and how we can change them.
OR
Does the processor driver (speed-step) automatically choose the voltage level for a frequency ?

Thanks,
Priya

[TimP]

A discussion here could hardly replace the Gentoo, IBM, or Red hat documentation, or possibly the cpufreq mailing list. Note that the Gentoo docs advise specifically against tinkering with the standard settings for "server" CPUs. In HPC usage, there is likely to be little running at 20-60% CPU utilization, so the primary decision for power saving is usually whether to enable Turbo mode.