My Mac just restarted itself!?!

[gavspen]

What the heck?!?

While playing a not very taxing sequence my computer spontaneously restarted itself for no apparent reason. It wasnt a brief power outage, since that would have shut it down but not restarted it (right?). It just bloody well restarted itself!

I've seen it do lots of weird stuff–we all have–but I never saw that before. Anyone else had this happen to them?

Gavin

[cuttime]

Any chance Ctrl+Cmd+Eject was invoked on your keyboard?

[billf]

While playing a not very taxing sequence my computer spontaneously restarted itself for no apparent reason. It wasnt a brief power outage, since that would have shut it down but not restarted it (right?). It just bloody well restarted itself!

Is this a Mac Pro or a laptop? If it is a Mac Pro, and it is not running through a UPS backup system, then yes, a very brief power surge/dropout can cause it to restart. And by "brief" it might be something you would not even notice.

[gavspen]

Any chance Ctrl+Cmd+Eject was invoked on your keyboard?

No chance. I was strumming away at the time.

[gavspen]

While playing a not very taxing sequence my computer spontaneously restarted itself for no apparent reason. It wasnt a brief power outage, since that would have shut it down but not restarted it (right?). It just bloody well restarted itself!

Is this a Mac Pro or a laptop? If it is a Mac Pro, and it is not running through a UPS backup system, then yes, a very brief power surge/dropout can cause it to restart. And by "brief" it might be something you would not even notice.

Mac Pro. So you're saying that a brief surge/dropout will do just that? Why wouldnt it just shut down, as it would if you unplugged it?

[stephentayler]

hmm - this happened to me today as well - I was on Safari when it happened…

very freaky...

SWT

[billf]

While playing a not very taxing sequence my computer spontaneously restarted itself for no apparent reason. It wasnt a brief power outage, since that would have shut it down but not restarted it (right?). It just bloody well restarted itself!

Is this a Mac Pro or a laptop? If it is a Mac Pro, and it is not running through a UPS backup system, then yes, a very brief power surge/dropout can cause it to restart. And by "brief" it might be something you would not even notice.

Mac Pro. So you're saying that a brief surge/dropout will do just that? Why wouldnt it just shut down, as it would if you unplugged it?

I live in an area where power outages happen frequently when the weather is bad, so I have experienced this many times if my Mac is not hooked up to a UPS (which it is all the time now). Anyway, if the outage is so brief that you might only notice a very slight light flicker, the Mac will restart if it is not on the UPS backup. If the outage is longer than a few seconds, then it will cut off.

[gavspen]

hmm - this happened to me today as well - I was on Safari when it happened…

very freaky...

SWT

Somebody cue up the Twilight Zone theme

[gavspen]

I live in an area where power outages happen frequently when the weather is bad, so I have experienced this many times if my Mac is not hooked up to a UPS (which it is all the time now). Anyway, if the outage is so brief that you might only notice a very slight light flicker, the Mac will restart if it is not on the UPS backup. If the outage is longer than a few seconds, then it will cut off.

Well well. I've lived in the same location here in NYC for 20 years and never had it happen before. Oddly, when the central air cycles on it sometimes does makes the lights blink (slightly) and it's never make the Mac behave strangely. Just another reason "Save" is your (best) friend. Happily I didnt loose much.

[billf]

Well well. I've lived in the same location here in NYC for 20 years and never had it happen before. Oddly, when the central air cycles on it sometimes does makes the lights blink (slightly) and it's never make the Mac behave strangely. Just another reason "Save" is your (best) friend. Happily I didn't loose much.

FWIW, I believe there is a setting somewhere in Preferences that can tell the computer to restart after a power failure. There is also one to restart if it freezes. I'm not sure if this affects your situation at all, nor do I remember offhand where it is in the Preferences.

All that said, I highly recommend using a UPS backup system no matter how reliable your power might be. It's saved me a few times.

[Prime Mover]

I had a computer start doing that once (a PC). I'm fairly sure it was the power supply... I changed it out and it fixed it, but I did a bunch of other things at the same time, so I can't be positive.

Brief surges and power interruptions will indeed restart a computer, not just shut it down. I'm not sure the technical reasons, but we have bad power in our area, and every time there's a momentary interruption, the computers all reboot. I've seen some fast enough that the computer stays up (probably the capacitors hold enough juice to stay up for about 1/8second). If it's longer than about 2-3 seconds, though, it'll stay off. But the average length power interruption will typically cause computers to immediately restart.

However, if you didn't experience any lights flickering or anything like that, it's probably not an external cause. Most likely the power supply is having difficulties. The result is about the same, but you won't see other lights and devices be effected.

Electric power is a strange and complicated thing. I've often had weird power problems that I've fixed and not known how. For instance, even if your power supply is starting to get finicky, there's probably something that's causing it to fail, otherwise the computer would just never turn on. It's very possible that you've got some power fluctuations on that outlet, but not enough to effect most devices. See if you can find a very robust power conditioner, might solve the problem.

[bayswater]

It wasnt a brief power outage, since that would have shut it down but not restarted it (right?).

Depends on whether you set the preference for it to restart after a power failure.

[bdr]

My Mac Pro started doing that fairly often, turned out it was overheating. Bust open the chassis and make sure the video card fan and all the other fans are clean.

[mikehalloran]

My Mac Pro started doing that fairly often, turned out it was overheating. Bust open the chassis and make sure the video card fan and all the other fans are clean.

Yep. That's a thermal overload.

FWIW, I believe there is a setting somewhere in Preferences that can tell the computer to restart after a power failure.

Yep again. You set this in Energy Saver, if I recall.

[dubiousmaximus]

I had a problem where my Mac Pro rebooted without warning every 20 minutes. Finally it was traced to a faulty memory riser, the card on which DIMMs are mounted. Luckily the machine was under warranty because my local service provider tried everything else first - replacing the PSU, the DIMMs and the hard drive. Frustrating experience and it made me sentimental about my Tascam 4-track from the 80's