undervolting cpus

[T400plus]

why does decreasing a processors voltage(VId?) decrease its heat showoff.
Does it run slower if set to lower voltage ?
Inparticular i am doing these on a pentiumM bianias 1.6 GHZ ...(still working T41)

[visionviper]

Just changing the voltage does not make the CPU run slower or faster, but it does change the amount of energy converted to heat because of resistance.

[T400plus]

thank you.
I have replaced the banias 1.6 with a 1.7 dothan , expecting to run faster and
cooler ignoring advice of seasoned users around here .

[ajkula66]

Dothan 1.7 should run cooler - if not noticeably faster - than a 1.6 Banias.

[T400plus]

yes, I realised that.
I had changed the HD to a super 5400 120GB (seagate) when my 40GB refused to boot.
That turns hot ..say...after 45 mins. and i cant do anything about that..till i junk the HD.
The left of the T41 is comfortably cool with the fan on,even with power setting at maximum
performance.

T41 2374-7FU,1.5Gb,1.7Ghz(SL7EP),120GB....