[mythtv-users] OT (?) heat/noise: underclocking vs. cpufreq

[Andrew Dodd]

Quoting Franco <net.surfer at tiscalinet.it>:

> I hope this isn't too OT; however I recall
> somebody recently wrote that the heat/noise issue
> is interesting for most mythtv users.
> 
> I found http://www.silentpcreview.com/ an excellent source
> of information on this regard. Among the other things, they
> have a (partial) list of motherboards that easily allow
> undervolting/underclocking (click on recommended ->
> undervoltable motherboards).
> 
> Before I make my purchase based on this partial list,
> do you know about other undervoltable/underclockable
> motherboards, that are not in that list but are maybe
> more suitable for a mythtv box?
> 
> I also have another big question: ;-)
> did anybody try to play with the "cpufreq" module?
> Does it work?  It would be very nice to be able to 
> change the CPU frequency on the fly... one could
> make a powerful/hot/noisy box for normal usage,
> and then make it slow/cool/silent when he wants to 
> listen music...
> 
> One could also fine-tune the best tradeoff between 
> speed and noise, without having to buy a dozen
> different processors for trial and error... ;-)
> 
> Franco

CPUFreq patches for 2.4 - Pain in the arse to get one that works with any recent
kernel.  The last one I got to work was 2.4.18 (Maintenance of the 2.4 cpufreq
patches is...  lacking.)

CPUFreq in kernel 2.6 works very well if you have a supported CPU/chipset.  I
believe the p4-clockmod module works with any P4 processor and only scales
frequency but not voltage, but I'm not sure.  The Speedstep variants only work
with mobile chipset/CPU combos.  (speedstep-ich and p4-clockmod both work well
on my Dell Inspiron 8200)

I'm hoping that eventually p4-clockmod capability is added to the speedstep-ich
module, as both CPU scaling methods CAN be used together, unfortunately to do it
with CPUFreq requires loading/unloading modules currently.