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





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