CBFalconer wrote:
Ben Pope wrote:
General Schvantzkoph wrote:

Power is V^2/R so reducing the core
voltage reduces the power dramatically.

I think that heat production in a chip is more about capacitance
than resistance. The voltage and capacitance (and switching time)
will affect the amount of current that flows, and that will
determine the heat production.

In CMOS logic the action consists of charging and discharging many
small capacitances at the clock rate. The charge q transferred is
proportional to V and C, i.e. dQ = CV. The time interval dT is
inversely proportional to frequence, so the effective current I is
dQ/dT, and the effective power is V*I. Since q is proportional to
V, that gives the usual power vs V squared relationship, but power
is also directly proportional to frequency.

Just keep your eye on the fundamental ball, power is voltage times
current.

I good point well made. Much better than I tried to make it. :-p

Ben
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