Randomly Turns Off

Note that I just got my MacBook into the repair center at my local Apple store. The genius wanted to see the failure while booting from a diagnostic f/w disk he had.

I should have checked to see if that disk was 10.4.7 or what. But as I was easily able to recreate it (wipes sweat from brow) by opening Terminal and running "yes" (NOT redirecting to /dev/null), the tech accepted that it was a hardware problem.

If the disk I booted was 10.4.7, guess it could still be an OS issue. Or if when I installed 10.4.7, it did a firmware upgrade on my behalf, perhaps it's a firmware issue. But it certainly smells like a hardware issue to me.

Note that I 'proved' there was an issue to the genius at the bar by running yes WITHOUT redirecting to /dev/null. I think this exercises the system a bit more since it forces the console to scroll as well.

I was never able to get it to shutdown with a yes > /dev/null. yes by itself, twice. Rendering to disk image from iDVD, twice. Everything else pretty intermittent.

Just for the hey of it, open up terminal and type in
yes > /dev/null & yes > /dev/null

Run it for a few minutes, until you hear the fans
kick in and see if it can do it without shutting
down. This test simply maxxes out the CPU, and won't
harm anything since a healthy system should be able
to do this w/o issue.

My system cannot do this for very long without
turning completely off, and I've tried it with other
RAM chips -- so it's not a RAM issue.

Nick

No, it's a definate logic board flaw. Heck the fans don't even come on during the test. Just got off with Apple Care and per the 2nd Level Tech: Temps at idle of 60+C are out of spec and will cause shutdown.

In most cases it's a faulty sensor, or if you will, logic board. Again per Intel:

""Intel Core Duo technology implements a new multiple-core thermal control algorithm. Both cores synchronize action requests and activity. A programmable policy can select DVS on both cores and linear control on each core either independently or as a locked operation. PROCHOT was also made available as an input, to allow thermal protection of platform components such as the voltage regulator (VR).

A finer grain overheat detection is performed by monitoring the thermal activity. If an extreme thermal condition occurs (fan malfunction, operation within a bag, etc.) the processor self thermal management may not be sufficient and the temperature may not drop below the threshold point. The internal control algorithm tracks the control behavior and further reduces power as needed. Continuous extreme conditions will eventually initiate an "Out Of Spec" thermal interrupt and register the warning in an internal status bit. The "Out Of Spec warning" signal is intended to initiate a managed system shutdown before a THERMTRIP shutdown occurs."

This "Out of Spec" signal comes when either one or both core exceed temp. Some have said that their Macbook wasn't hot at the time but "hot to the touch" or even using program isn't the issue of whether or not the shutdown occurs. For instance if the fan isn't operating correctly, or even if the processor runs below spec rated temp."

thanks for the trick
seems more efficient than the quicktime hd one

i updated the website
http://racr.free.fr

Interestingly I see that no-one is talking about Powerbooks but my G4 15" 1.67GHz bought in August 2005 in the UK has also suffered a logic board failure since installing 10.4.7. Apple have also told me that they will be replacing the hard drive (no idea why - heat?).

Basically I took it into the Genius Bar in London and they confirmed in the system log that temperature was the cause of the random shutdowns I was experiencing.

So is anyone else having trouble with Powerbooks and 10.4.7?

I've been dealing with exactly this problem since I bought my MacBook the first week it shipped. After having my MacBook repaired for this problem about 2 weeks ago, I've been having the very same problem develop again. Here's some background: This unit is my second one, as my first unit had a bad fan bearing the night I took it home. It was exhanged by the Apple Store the next day. The second MacBook worked great for about 10-12 days. My MacBook started randomly shutting down, typically while it was plugged in. I also noticed that the MacBook was quite hot, and CoreDuoTemp was showing 68-69 deg C. when it did this. My MacBook sleep light would stay on even with the lid closed in this "heat frozen" state, and would not restart until it had sufficiently cooled down. The other notable aspect was that the fan was not coming on at all (I can hear it when it is running, when it does run, that is...) This undoubtedly led to the thermal runaway of the CPU to the point where the computer shuts down when it gets too hot. My hypothesis for the random shut-down syndrome was due to the MacBook overheating due to the fan never coming on. After figuring this out, I took it to two different Apple Stores, and both technicians agreed that the fan was not coming on. It was duly sent back to Apple on June 23rd for repair...it was returned on June 27th with a new motherboard.

All was fine until last week, July 13th, when I noted that the computer did not go to sleep when I closed the lid when running Windows XP...a few minutes later, it was very hot, the screen was black and the fan was on. Since then, my MacBook has been shutting down after being on for 20-25 minutes, which is about how long it takes to get hot to the point where it shuts down. I can literally start it up, open the screen to view, and sit there and watch the temps soar using CoreDuoTemp to the point where it just shuts down again. just as it did with the original motherboard on MacBook #2. This evening I had the computer on just reading email, noted it was getting very hot; CoreDuoTemp said it was at 70 Deg. C, and right about then, it promptly shut down, and would not restart until it had cooled down,and the fan does not appear to be working. I seem to have developed the very same problem all that prompted a motherboard replacement all over again. It was sent to Apple for repair on June 14th, and I still have not received it back yet.

MacBook Mac OS X (10.4.6) 2 Gb 3rd Party RAM

MacBook Mac OS X (10.4.6) 2 Gb 3rd Party RAM

The random shutoff happens immediately after I power up. Especially if it hasn't been on for several hours. Once I turn it on, the fan immediately runs very loudly and then as soon as the fan turns off and its only been on long enough to get to my desktop, sometimes long enough to bring up Safari, it shuts off. When I turn it back on, I hold the power button down until I get that loud beep, after that it stays on! Im not running anything to work it hard, and its not hot. Does this still have anything to do w/ the temp issue?

Same trouble with my Macbook shipped in Paris 06-2006.
No trouble after swithing RAM from each slot.


Macbook white 2GHz Mac OS X (10.4.7)

apple told me by friday i can get my new computer, but they just called me and told me they had some new machines in. they gave me a new computer! cant complain. hope this one doesnt start shutting down. thanks again apple! i love this company 🙂

Well, mine is off for repairs. Hopefully it won't come back as no problem found.

I have spent more hours troubleshooting this thing and had to endure more crashes in the last 4 weeks than in the last five years with ibm thinkpads.

With that said, let me leave you with the number one reason to own a mac according to apple.com:

"Your toaster doesn’t crash. Your kitchen sink doesn’t crash. Why should your computer? Think of the countless hours you would save if your PC worked on your time — not the other way around. Then think about a Mac."




White Macbook Mac OS X (10.4.7) 2.0GHz | 2GB RAM | 100GB 7200RPM HD

OK, I'm a victim, too 🙂
week 21 macbook, started turning off randomly around July 1.
My experience:
- it comes in waves
- resetting the PMU does help
- it even happens in "firewire disk" mode
Apple has shipped me a box to send it in for repairs.

BTW, when talking to them on the phone, it was apparent the support agents are not very aware of the problem yet. I referred the (quite helpful and courteous) support person to this discussion and he was quite interested to take a look.

I experienced the same problem (random power shutoff followed by rainbow vertical lines on LCD) and shipped my MacBook back for repair yesterday. Its current status is "On hold - Part on order" which leads me to believe this all stems from the faulty logic board issue mentioned in the thread. I just hope they don't replace it with the same hardware and I end up in the same situation a month from now.

This is actually my second repair on the product. I had to ship it back about a month ago for a faulty speaker. I definitely should've listened to my friend (an avid mac user) who told me "Never buy a first release Apple product".



MacBook Mac OS X (10.4.7)

MacBook Mac OS X (10.4.7)

Bought a Black Macbook (week 27? serial is 4H627) on Saturday, that same night I started experiencing the random shut downs. I had upgraded it to 10.4.7 a few hours before. Would shut down anywhere from 2 seconds to 5 minutes of uptime.

I took it back to the apple store the next day, luckily it shut down twice while the guy was looking at it. I asked him if he had heard of this problem, he said no he's never seen this before. I told him it was the most popular thread on the Macbook forums and that there were tons of us with the same problem. His response was essentially this: he intentionally does not browse the support forums because people dont usually have the same problems so its impossible to tell if anything is related.

Regardless, I asked for a new computer and he gave it to me with no hassle. I've been running my new machine for the last two days and it has been working perfectly. I've yet to update to 10.4.7...I want to try it for a few days on 10.4.6 to make sure nothing happens. This new machine is a week 28.

I find it rather discouraging that a Genius Bar rep would not browse through the support forums. Its true that alot of people have many different problems but how else would you know what the problems are. And besides this thread alone is the most popular. Im not telling anyone how to do their job but if I worked at and Apple Store (at the Genius Bar) I would keep up to speed on what is being discussed in the support forums...just my 2 cents.