Random Shutdown: Locked Clockspeed, Processor Voltage Correlation?

Question

I use Hardware Monitor to keep track of more sensor readouts than just temps. I recommend everyone install it. Using it, I've discovered some weird behavior in the processor clockspeed and voltage that correlates in a predictable with my typical macbook random shutdown problem. I wonder if others witness the same correlation.
Normally, according to my sensor readings, the clockspeed and cpu voltage fluctuate frequently and continually, presumably according to the demands on the processor. Clockspeed typically runs between 1333Mhz and 2000Mhz, voltage between 1.00 and 1.30V.
When running like this, it is subject to random shutdowns at any time, but most especially — indeed with absolute reliability, so to speak — within ten minutes of waking from sleep — regardless of whether i'm using mail, surfing, playing music, or running intense calculations and (so far as i can tell), regardless of how many or few processes are running simultaneously, and regardless of temperature readings. Indeed, now with the new firmware update my temps are quite low. In fact, since the computer most reliably shuts down soon after waking up, it's temp at shutdown often registers no more than the mid-50s (it'll shut down at 47).
After the macbook shuts down, it refuses to restart reliably with a simple press of the power button. Like many others, I have to hold down the power button for about ten seconds, until I hear the pained protracted beep, before the computer will enter into the normal booting process.
After it boots up like this from a shutdown — and this is what I haven't seen enough commentary on — the processor speed remains locked at 1000Mhz and the voltage at .99V until the computer goes to sleep again.
While the computer is locked into this slow-clockspeed-low-voltage mode, it is absolutely reliable. It never shuts down randomly. It runs much slower. Which is really noticeable and frustrating when using any graphics-intense or movie app.
So my questions are:
Does anyone else experience this sort of locking processor behavior?
Why would the processor lock like this?
Is it possible that the sensors are wrong? That in fact the processor is fluctuating normally but now the computer doesn't "know" it?
How would the processor's ability to vary its clockspeed and the voltage it draws affect its propensity to shutdown randomly?
I would be grateful for the observations of others regarding clockspeed and voltage at shutdown and after rebooting.
Thanks.
macbook 2.0 Ghz, 1.25GB, 80GB, week 20 Mac OS X (10.4.7)

Answer 1

hi
I have exactly same problems and symptoms.
It was a refurbished week 20 unit from apple uk it arrived in excellent condition and worked perfectly for two weeks without the fan comeing on at all it was perfectly quiet but hot.
As this was my first mac I was unaware that this was abnormal I had heard that they ran hot but being new to mac I was on a learning curve. Then two days after the remorse return period it began to shut down the first time was after a period of sleep just after I opened the lid. It then was and still is impossible to start it from warm or cold in the normal way, but only by holding the power down until beep. Then it will work for days at 27 deg c without a problem all be it at the 1 gig reduced speed which as you say is frustrating to say the least. Applecare UK don't acknowledge the problem at all they just want to treat it as a normal warrenty repair at my inconvenience. I am at present awaiting a more generous response from apple. I'm demanding a replacement unit but they just want we to fill out their standard web questionaire. (with non relavant tick boxs) If only one could speak to a real knowledgeable individual at apple I'm sure I'd get some satisfaction. But in this age of executive big bonuses what can one expect.
I hope Apple get real with this soon because the disscussion forums are getting overloaded with this issue its getting harder to login have you noticed.
yours unhappy customer.