Random, Sudden Shutdowns - A redux and other things to rule out first

Question

Do a google search for "macbook random shutdown" and you'll find many people with similar problems reporting on various forums. At present, this issue has not been picked up by the mainstream PC news media. However, one should also note that only a fraction of those with problems are suffering this particular fault. A large number of other reasons must be ruled out before a MacBook owner should become convinced their machine is one which suffers this problem. Bad RAM, poorly seated RAM, improperly installed hard drive, corrupted OS, corrupted plists, bad batteries, bad chargers, corrupted PMU, and corrupted NVRAM all need to be ruled out first!
My own MacBook suffered the random sudden shutdown malady and eventually required complete replacement after a logic board replacement did not solve the issue. Some of the MacBooks appear to have a hardware problem which surfaces after a period of use. Many reported their problems starting after a month of ownership. Coincidentally, that also coincided with the release of 10.4.7, but most likely that is not at the root of the sudden, random, shutdown problem.
(However, 10.4.7 is strongly implicated in a separate MacBook problem - colored vertical lines during boot on some machines. That is probably a separate issue.)
Description of the Random, Sudden Shutdown Problem
MacBook suddenly shuts off to a completely powered down state seemingly at random. There are no kernel panic, mouse freezing, or other premonitory symptoms. The machine simply powers down suddenly. The screen goes black. The hard drive spins down and no sleep light illuminates. The machine simply turns itself off.
The shutdowns may occur on either battery or with AC adapter attached. Some owners report their MacBook is less prone to sudden shut down while on battery vs AC adapter. My own afflicted MacBook would suddenly shutdown on a fully charged battery or on either of two AC adapters.
The shutdowns occur with either 10.4.6 or 10.4.7 OS loaded. I went through several cycles of clean installs of the base 10.4.6 and the Intel Combo update to 10.4.7 before it became clear that it mattered not which OS was running. Another indicator that this is not an OS issue is that sudden shutdowns can occur in target mode and also when running just the Apple Hardware Test - which relies on minimal software to operate.
The shutdowns tend to grow more frequent once they begin. They may worsen to the point that a machine will not complete boot up before shutting down. It may take several power up presses to start the machine. Oddly enough, a machine that had difficulty starting up, may be easy to start up several minutes later. It may run for hours or minutes before another sudden shutdown. The frequency is low and random enough that is very difficult to demonstrate this fault to a service technician.
Some users are able to induce a sudden shutdown by running their CPU's at high load and thus heating up the machine. This is easily done by running the yes command in two Terminal windows. Some users report their MacBook is more prone to sudden shutdowns when their CPU is relatively cool. The bipolar reporting is confusing. There may be more than one type of sudden shutdown being reported. One due to CPU overheating and another due to another hardware problem which has yet to be elucidated.
Resetting of the PMU and PRAM MAY temporarily reduce the frequency of the sudden shutdowns, but the effect is temporary. Indeed, the effect may not even be real given the randomness of the shutdowns. None-the-less, one must perform PMU and PRAM resets to ensure that some corruption of those devices is not creating a reason for shutdowns. On my own MacBook, resetting PMU and PRAM (four chimes) did not prevent the random sudden shutdowns.
The sudden shutdowns occur with well seated stock RAM, replacement RAM, and reseated/replaced hard drives. Swapping out and testing both RAM and hard drive helps to eliminate those as the source of the problem. On my own machine, I exchanged the RAM and the hard drive to eliminate them as the cause. This made it considerably easier for the Apple genius to decide it was an internal problem.
In my case, a logic board replacement did indeed solve the fault, but several days later, sudden shutdowns began again. Presumably either the replacement board has the same weakness as the original or some other component of the machine was the actual reason for the sudden shutdowns. The former is quite likely because the machine was made stable for several days with a new logic board. At that point, I requested to be swapped to a new machine and the Apple Store manager wisely decided to help out his customer. For that I am most grateful. However, it is unlikely that the majority of people will have their machines swapped out, but instead repaired.
At this time, no official statement regarding cause for or acknowledgment of the MacBook's sudden random shutdown problem has been made. Because the underlying cause has not been revealed, it is impossible to know that a logic board replacement will permanently solve the problem or merely result in the same fault recurring later on the replacement board. Of course, we do not know if it actually is a logic board flaw.
My advice to MacBook owners whose machines develop the sudden random shutdown symptoms are to...
1. Get your data backed up immediately. The machine will likely suffer more and more frequent shutdown events.
2. Revert to stock RAM and hard drive if you have installed after-market replacements. You must do this and see if the shutdowns continue to occur. Otherwise, the first thing blamed will be your RAM and hard drive.
3a. Perform a PMU reset, by shutting down the MacBook. Removing the battery. Disconnect the AC Adapter. Then, press the power button for five seconds. The reinstall the battery and mains adapter. Restart the machine.
3b. Reset PRAM by holding option-command-P-R keys down during startup until you hear the chime at least three or four times.
Resetting the PMU and PRAM are standard procedures you'll otherwise be asked to perform to diagnose your machine.
4. Do a CLEAN install of the OSX if you wish to totally eliminate a bad OS install as the problem. This will destroy all your data. Alternatively, an archive and install will be helpful without totally destroying your data, but that will not let you exonerate your system files and settings. An alternative is to run Apple's hardware test utility which is found on your OS installation disc. However, an extended hardware test is needed because the shutdown flaw may take hours to surface.
Note: If your MacBook has become so "narcoleptic" that it cannot even complete a boot up sequence, try holding the power button down until you hear a loud beep. That may allow an otherwise balky machine to start.
Once you have done the above, and are still seeing random sudden shutdowns, you have largely done the preliminary footwork that you'll need to prove whether your MacBook has this particular problem and not something more common. Then, call AppleCare or visit your Apple Genius to have the machine repaired or replaced. Hopefully, the root cause of this problem will be discovered, disclosed, repaired and prevented. For now, it appears only a fraction of the MacBooks are suffering this fault, but the machine population is still young. Overall, the MacBook is perhaps the finest laptop I've bought from Apple. It will be nice to trust the machine to not lose my work.
BTW - resetting PMU may induce a separate 10.4.7 related bug which results in your MacBook exhibiting a white screen with progressively more numerous vertical color lines during startup. This appears to be fixable by resetting PRAM and then temporarily changing display resolution to something other than the current setting and then back.

Answer 1

thanks for the comprehensive info. i experienced this for the first time today. i bought my macbook the day they were released. the shutdown happenned for me after leaving my computer on overnight with no programs running. about two minutes into web browsing it shutdown. it then shutdown in the middle of restarts. i disattached power cord, external hard drive, dvd burner & ethernet & it powered up and has been working for about 20 minutes since.
this computer has really been a lemon. first my superdrive scratches the **** (just previewed this, i can't believe they sensor the h_ word?) out of discs, then the trackpad button becomes very hard to push. i've been working around those issues using an external dvd burner and mouse, but not sure how to work around sudden shutdowns. i haven't been able to send it in for repairs yet since i bought it cause i needed it's dvd authoring capabilities for a class i was taking, plus i wanted to make sure nothing else went wrong (self fulfilling prophecy?). i was planning on taking it on vacation with me, but guess i better pack my old ibook too (which other than a cd burner which sucked from the start, has been very reliable). i'll send in my macbook when i get back.
anyway, thanks for the info & advice! i'll back up my crucial data now.
white macbook, 2GHz, 1GB ram (factory installed) Mac OS X (10.4.7)
macbook Mac OS X (10.4.6)
macbook   Mac OS X (10.4.6)