Why backwards I said frquency does not reduce heat as much and
voltage decreases I forgot the square, but in the real world I have
not seen a square reduction of heat emmitted during a voltage
reduction, this might be because at the same clockspeed while the
current to the processor is reduced during reducting the voltage it
is at times not linear. and heat is actually a function of watts
supplied - whatever is actually used to perform work. watt= voltage
times current and ohms law seems to run into a snag with
micropocessor setup's I dunno why.
terramir

--- In Silent-PC@yahoogroups.com, "Chris Thomson" <cmthomson@...>
wrote:
>
> Well, that's backwards.
>
>
>
> CPU (and any other semiconductor) power consumption is linear with
the
> formula V*V*F, that is, the square of the voltage times the
frequency. So
> undervolting is the best way to reduce power consumption. Of course
at some
> point the CPU becomes unreliable when the voltage is too low. Core2
CPUs are
> designed to be reliable at a reduced clock speed (typically 6x) at
1.05V.
> Many are reliable at full clock speed at this voltage, and some are
reliable
> at even lower voltage, but few can be run below 0.9V.
>
>
>
> To answer the original question: the reason to undervolt is to
reduce power
> consumption, which in turn reduces cooling requirements, which in
turn
> reduces the needed fan speed, which reduces the sound level of the
system.
>
>
>
>
>
> -----Original Message-----
> From: Silent-PC@yahoogroups.com [mailto:Silent-PC@yahoogroups.com]
On Behalf
> Of terramir
> Sent: Sunday, June 29, 2008 6:59 PM
> To: Silent-PC@yahoogroups.com
> Subject: [Silent-PC] Re: Undervolting Intel Core2 Duo?
>
>
>
> Q:> I only have one question - why undervolting?
> >
>
> A: Because heat generated is a function of clockspeed and voltage,
the
> less voltage you feed a processor the less heat it will generate,
so if
> a cpu is stock speed of let's say 1800 Mhz like the core2duo 4300
and
> you run it at let's say 1200 mhz you have a slower computer that
gives
> off less heat, however the heat reduction is not linear with clock
> speed, the reduction of watts drawn(heat produced) at the same
voltage
> is actually not 66% like that 66% of clock speed but more like a 80
to
> 90% of the original heat produced, however on voltage the
reductions
> are almost linear, so at the same clockspeed if you can reduce the
> voltage by 25% you'll get like a 20 to 25% reduction in heat
generated
> there are some fudge factors there.
> and with less heat generated you need less cooling ergo you
generate
> less noise.
> terramir
> BTW the guy with that board at stock speed I doubt you could go
below
> 1V and the absolut minimum will probably be around 0.85V @ 33%
under
> stock speed. lower than that I can't tell you because I can't
> manipulate my board that much.
> However I have run a C2D 4300 @ 2700 Mhz (50% overclock) with about
> 1.175V- 1.212V so they are3 good undervolters on prinicipal, but
> becareful if you undervolt you want to make sure that you have
disabled
> the power management options or fine tuned them because that's how
my
> c2d crapped out a few times when at idle the power mangement
options
> could reduce your voltage even further hence putting you under a
> working limit so use a utility where you can specify the voltages
> during power management. (remember if the bios overrides the
voltage
> you'll not have true vaules neccesarily in the utilities so go
higher
> first and see if it's stable by locking the power mangemnt options
and
> toasting it with a burn-in utility.
> terramir
>
>
>
>
>
> [Non-text portions of this message have been removed]
>