Undervolting a Macbook Pro

hi -

may i ask where you heard this? i suppose you're going to breadboard your own transformer? please be aware that any mistake you make might fry your motherboard, at least, or you, since you'll be dealing with line voltage...

if your machine is running too warm for you, consider an iLap or any of a number of similar devices which do nothing more than widen the airgap below the machine to allow more heat to radiate away, instead of being trapped under the machine.

if your battery life seems too short, have you recalibrated it recently? have you tried resetting the PMU? both are very easy to do.

i have no experience w/ overclocking your GPU, but as i allude to above, you seem to be walking down a very strange path here...

i'm still be interested in hearing where you heard about how undervolting would improve battery life and temperatures... plz post back w/ that - thanks! cheers

I've used RMclock Utility to undervolt in xp (i think thats its name anyway). I haven't booted into xp for a while but i think i took the core voltage down to 1.1v or 1.087 and it ran fully stable whilst gaming with the graphics card overclocked. The undervolting significantly reduces heat output and prevents thermal protection cutting in when gaming with an overclocked graphics card. If you undervolt too far the computer just freezes. I don't know if this can permanently harm the computer but its always fine on reboot, it doesn't take long to find the lowest appropriate voltage.

Just get an iLap. With nothing more than better cooling, I get 30-45 minutes more use off the battery. I also condition it every month.

I had a bad battery before the replacement program, but once it was replaced, and using the newest firmware, the MBPro runs at least 5-7 Centigrade cooler, averaging ~ 55 C during normal use.

Granted, if I try to run something power hungry iMovie rendering, World or Warcraft, I see a bit over an hour of use and a lot of heat.

I would be extremely paranoid about playing around with the power. How many extra minutes of battery use make the potential damage to the MBpro worth it?

I would be extremely paranoid about playing around
with the power. How many extra minutes of battery use
make the potential damage to the MBpro worth it?

not only that but your warranty would be void when they find out you were messing with the settings.

You can only undervolt In Windows it seems (pretty sure about this). I've used RMclock often and it works. However, it will not undervolt below .95v with the CoreDuo. The Pentium M will undervolt way down to .7 volts.

With the Duo You can only undervolt the upper speedstep voltage region but this will definitely help reduce heat for demanding apps like games.

It's totally safe as only 'overvolting' could hurt the system. Don't listen to anything else as no matter what literature people come up with- it's just common sense. You can't fry a circuit by underpowering it. Go to the Rightmark (Rmclock) forums. You will see the are no cases of damage do to undervolting.

Actually, you CAN fry a circuit by underVOLTing it (not the same as underPOWERing). By reducing the voltage you can cause it to draw more current, which can then cause a thermal melt/breakdown.

That, however very probably doesn't apply to CPU's and GPU's, or, at the very least, i've never heard of anything bad resulting from undervolting.

You can undervolt with a program called "Coolbook Controller"

( http://www.coolbook.se/CoolBook.html $10)

It works well and also lets you set the Frequency your processor operates at (useful for clocking down to 1 ghz when on battery doing light work).

I have succesfully run my original 2ghz macbook full out, at a voltage setting of 1.1 (instead of the 1.25 default) - My computer is an average of 4 degrees cooler (celsius) when almost idle and up to 14 degrees cooler when maxed out. My fan is also much less active at the idle temp (and the Clock speed is not stepped, but set to 2 ghz) to get this lower temperature.

PS - the programmer seems like he may be into questionable forum posting practices (ie - logging in as other names to support his program - I've read some weird threads on a few different sites) but the program itself seems solid - It has made my Macbook much quieter as well as cooler, which is what I was really after.

Cheers