[mythtv-users] Laptop CPU in Desktop Mainboard

Steve Adeff adeffs at gmail.com
Wed Jan 25 14:49:41 UTC 2006

On Wednesday 25 January 2006 05:12, Jo Shields wrote:
> Robert Tsai wrote:
> >On Tue, Jan 24, 2006 at 09:37:24PM +0100, Marius Schrecker wrote:
> >>>Tom Dombrosky wrote:
> >>>>On 1/24/06, *Steve Adeff* <adeffs at gmail.com <mailto:adeffs at gmail.com>>
> >>>>wrote:
> >>>>
> >>>>    On Tuesday 24 January 2006 12:34, Michael Starks wrote:
> >>>>    > I have been thinking of using a laptop CPU to save power on
> >>>>    > a new MythTV system.  Basically, I'd like to be able to use
> >>>>    > the cpuspeed daemon to drop the CPU speed when there isn't
> >>>>    > a lot going in.  Has anyone done with with a full-size
> >>>>    > mainboard?  Any other tips?
> >>>>
> >>>>    laptop CPU's use different sockets, etc. I believe some of
> >>>>    the new mini boards (BTX or something?) use laptop cpu's. I
> >>>>    also believe desktop cpu's support the cpu speed daemons.
> >>>>
> >>>>The Athlon laptop cpus use the same socket.  They will work fine.
> >>>
> >>>A  really minor modificatio can turn a normal Athlon XP into a
> >>>mobile athlon too - which enables you to use the athcool stuff
> >>>under linux. It's pretty straight forward and there's plenty of
> >>>stuff on doing it out there.
> >>
> >>What about the 64 family, any mods there? I'm using an Athlon 64
> >>3700+ San Diego (socket 939) which has pretty good voltage/speed
> >>stepping, although I'd love to be able to drop the lowest step even
> >>more. If anyone knows a mod for that I'd love to know! The kernel
> >>module seems to read the stepping info direct from the cpu or bios,
> >>and I haven't found a way to manipulate this manually, although
> >>googling suggests that a further 10% cut in voltage should be
> >>possible.
> >
> >How slow are you trying to go?
> >
> >I have an Athlon64 3500+ Winchester. By default, the cpufreq-ondemand
> >governor only lets it go from 2.2GHz down to 1.8GHz. I had to tweak it
> >manually to drop it down to 1.0GHz (nothing available in between):
> >
> >	# cpufreq-set --min 1000000 --governor ondemand
> >
> >[This is software only; no mucking around with voltage on the
> >motherboard.]
> >
> >--Rob
> There are desktop boards with Socket 479 on them - the form factor used
> by Intel's low-heat low-power high-speed Pentium-M chips - a Dotha-core
> Pentium-M is usually a little faster than an Athlon64 running at an
> identical clock speed. It also works fine with assorted cpufreq
> handlers, and can idle pretty slow as needed, then ramp up automatically
> when needed.
> My 1.7Ghz Dothan sits at 800MHz most of the time, and the
> temperature-controlled CPU fan rarely if ever bothers to spin.
> The problem (of course) is that Pentium-M, and compatible motherboards,
> are expensive.

how "safe" is letting the CPU change its speed? will it affect how 
applications run or is it seamless?


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