Ever since the Pentium (maybe earlier?  But at least everything after
the Pentium..), Intel has used techniques that have a lower clock
speed limit, ie, they are decidedly non-static.

There's a range of usable frequencies, but they aren't published, and
they vary from processor to processor.

Further, Intel has used various means to prevent
overclocking/underclocking on its lower-end processors.  There are
some that don't have these limitations, but they are the high end
expensive models.

Here's one article on underclocking an older AMD processor for desktop:
http://pcstats.com/articleview.cfm?articleID=1798

For the most part everything is programmable on higher end
motherboards, but I expect that to save cost, weight, money, power
laptops aren't nearly as flexible.  You may have some difficulty
adjusting the voltage at all, and may only have a few steps for the
processor speed.  You may not be able to modify much else without
getting a higher end laptop (portable desktop, alienware, etc)

Although I'm curious why you have requirements suggesting high power
(dual core, etc) but still want the benefits of long battery life and
low cost.  Performance, long battery life, low cost - pick two.

Have you considered a laptop with two battery bays?  Or a separate battery?

-Adam

On Nov 27, 2007 9:46 PM, Apptech <apptech@paradise.net.nz> wrote:
> Summary:
>
> How hard to UNDERclock an Intel laptop processor?
>
> ____________________
>
> A new laptop is in the offing.
> Minimum spec is "IBM compatible", dual core processor, 1 GB
> RAM, 100 GB HDD.
> PLUS - Longest possible battery life.
> AND    Small and light is good
>
> More or less as appropriate always good.
> Target price not over about $US1200.
>
> Uses will (of course) be varied but an  essential role is
> the capability to load photos from a Flash card while
> displaying slide shows or image manipulating. This is the
> main reason that dual-core is essential - it's not the extra
> speed (which helps) but the fact that, at least for the
> software I use, partitioning the two tasks one per processor
> makes a vast difference wrt running them on even the fastest
> of single processor systems. And, I don't wish to change my
> software.
>
> Any number of 'notebooks' meet the spec until light and
> long-battery-life are added.
>
> The 12.1" VAIO family do this superbly but get very
> expensive as the spec gets acceptable.
> Down to about 1.2 kg and 6 to 7 hours battery life in "slow"
> mode.
>
> The 12.1" HP (possibly some being made for them by ?ACER?)
> are excellent on weight but only OK on battery life.
>
> It seems to me that if I could massively underclock and
> undervoltage the CPU and run the backlight not too too
> bright that I should be able to obtain similar to VAIO
> results. Obviously speed will fall with underclocking but as
> long as clock speed is easily altered this is not an issue,
> and even if it took a reboot it would still probably be
> acceptable.
>
> Which leads to the question:
>
> AMD processors are, I read, all capable of being
> underclocked and under voltaged as they all use the same
> control, IC with this capability and there are utilities
> which perform this task well.
>
> BUT Intel processors are reportedly inconsistent in their
> ability to be underclocked.
>
> Can people comment on the issues involved ?:
> what it takes to be able to underclock and under voltage an
> Intel CPU,
> is it always possible,
> are there gotchas,
> have people done it ,
> did it work OK,
> and reliably,
> should I buy an AMD based laptop if this is a core (no pun
> quite intended) issue.
> ?????????????
>
>
>
>            Russell
>
>
>
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