[ltp] CPU Idle and whine

[Paul RIVIER]

Hi,

can you hear it at the lowest frequency ?
Actually I had this problem and the noise was loud when idle at high 
frequency.
My solution is described in the thinkwiki : i use a daemon (powernowd) 
with a policy that avoid idle at high frequency.
That way I nearly never heared the noise again.
Undervolting finished to solve that problem.

Regards


Paul

Richard Neill wrote:

> Dear All,
>
> I noticed that there is a faint(*) whine audible through the speakers 
> of the Thinkpad. It only occurs when the system is idle, so I think it 
> is caused by the CPU idle state [kernel 2.6,ACPI].
>
> My current "cure" for this is to run `nice -n 19 yes > /dev/null`
> so that the CPU never becomes idle and the noise doesn't occur.
>
> Of course that is not a good permanent solution! Furthermore, it uses 
> lots of power (not really a problem when on mains) and makes the CPU 
> hot (turning on the fan, which is noisy).
>
> Is there a better solution?
>
> (*)It really is quite faint (thinkpads are good quality machines!) - 
> only really audible with headphones (or an external amp), and with the 
> volume levels turned up high. It's at 1kHz though, so I'd prefer to be 
> rid of it!
>
> Thanks very much for your help,
>
> Richard
>
>
> P.S. Anyone else trying to squeeze max audio quality from the Thinkpad 
> - do play carefully with all the levels. gnome-alsamixer is probably 
> the most helpful mixer to see what's happening. Eg switch off any 
> channels you don't need, and, I found the 3D control should be on, but 
> the slider at 0%. Turn the software mixers up (about 90%), but the 
> main hardware volume down - this increases signal-noise ratio. You can 
> make quite an improvement in hiss and whine!