[mythtv-users] Laptop CPU in Desktop Mainboard

[Jo Shields]

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.