For those who have reset PMU . . . ?

It's your PMU and not your clock or processor or whatever chip. I don't think it will effect your clock. I reset my PMU just last night to try and fix a screen dimming issue. The auto dimming thing did not get resolved, however, my MBP is way cooler today than it was (I mean temperature wise). I'm going to "assume" that I actually reset the PMU, since one of the benefits is supposed to be a cooler machine - and I seem to be able to state that is true.....

Bob

I reset the PMU for an optical drive issue, which is still not resolved, grrr, but I did not get that message after the procedure. I also did not get that message a few months ago when resetting the PMU for some other reason.

Bob, So your saying resetting the PMU made your machine run cooler? Any idea why?

Paul - I have no clue! I read multiple posts on multiple sites that this would occur, so, even though I didn't think my heat was that bad - I decided to try it (scared to death I would introduce a whine or something as a result! LOL!). It just worked. And today was a good day to try it, because I was editing extremely large images in PhotoShop most of the day. I had no heat compared to before.

One of the posts suggested that thier fans weren't running right and reseting the PMU fixed that. That could be the case for me. I know my fans run, because I've felt the air movement in the back, but I sure can't hear them. Not like I could on my PowerBook.

Bob

Wow! So no adverse effects from doing it? How do i find out how to do it?

1) Shut down your computer

2) Remove the battery from your MacBook and make sure it is not plugged into AC power

3) Flip it back over (while still unplugged) and hold down the power button for 5-10 seconds.

4) Put the battery back in and plug your machine back into AC power. Wait a few seconds and restart.

Bob

Thanks Bob. I tried it. I would never know if mine whined or did anything like that cause my hearing loss is pronounced but my wife says hers and mine are dead silent as far as she can tell. I have really enjoyed this computer and she loves hers. My 12" PB sounded like a jet engine when the fans went on and even I could hear it:)

I do it a little different.

I shut down my computer....Then hold down the power button without letting it up. In a few moments, the sleep light will flash and there will be a tone. After the tone sounds, let go of the power button.

Then, press the power button to restart.

Bob...isn't this how it used to be. When I tried the thing without the battery in, I was not sure that there was an actual reset.

Is what I am doing resetting something other than the PMU?

I do it a little different.

I shut down my computer....Then hold down the power
button without letting it up. In a few moments, the
sleep light will flash and there will be a tone.
After the tone sounds, let go of the power button.

I am not positive and if anyone knows for sure please correct me. But, I believe that is the Programmers Mode like the old B/W G3's and G4's had the Programmers button. I thought that was used when installing firmware and such.

I don't think you necessarily get that message by resetting PMU, but I think you get it by resetting parameter ram. I always do both when I've reset the PMU. After resetting the PMU, press the power button, then hold down option-command-p-r until it bongs again, then let it restart.

When I do that I do get the message about clock being reset.

Could be....I just like the loud tone.

Bob,

Apple's page with PMU reset instructions says that resetting it will also result in NVRAM settings reverting to default. But they don't enumerate what's all in NVRAM. In particular, whether the clock is included in those settings is unknown to me.

I've noticed tremendous difference between my MBP's temperature when running on batteries (not hot at all) and on external power (quite hot) and was considering the PMU reset to see if it altered that pattern. But with the unknown consequences of a NVRAM reset lurking, I've yet to go ahead with that.

Randall Schulz

iMac 20" Core Duo; MacBook Pro Mac OS X (10.4.5)

I got the instructions from: http://docs.info.apple.com/article.html?artnum=303319

Bob

Randy,

If you happen upon information that suggest other than I'm saying, please be sure to correct me. I don't want to go down any roads that will cause anyone problems!

I don't know what NVRAM is - can you explain?

Bob

Bob,

NVRAM is a generic term—Non-Volatile RAM. In this context, it records various (and to me at the moment, unknown) low-level configuration parameters, especially things that are required prior to the system being sufficiently initialized to have access to disk-resident information. E.g., I think the speaker volume is kept there.

OK. Here's an article, not MacBook-specific, but probably fairly accurate and certainly suggestive of the general kind of information held in the NVRAM on a Macintosh computer:

http://docs.info.apple.com/article.html?artnum=2238


Randall Schulz

iMac 20" Core Duo; MacBook Pro Mac OS X (10.4.5)