Was having this same issue to the point to where, when my Mac Pro (2 x 3ghz Quad Intel Xeon Early 2008) would random restart, before the OS could boot back up again it would restart again and I was stuck in a terrible cycle until i unplugged and left the computer off overnight. Upon turning it on it would work fine then an hour or so later (sometimes a day or two) it would start happening again.
I monitored processor usage, temperature, etc and nothing was out of wack.
To make a long story short it was my graphics card. (ATI Radeon X1900 XT 512mb)
I had tried before taking all the compontents (HD, RAM, Graphics card) out and compress air to remove dust and it didnt work. After doing it this last time I realized on the back side of my fan (on the graphics card) was a vent. I could not see it due to a 2 inch thick gray wall of dust that had settled and packed so tightly over it that it matched the color of the gray fan and looked like a simple solid plastic piece. I sprayed it with the compressed air and lo and behold after the duststorm settled i saw the vent that was buried underneath.
I would hear the fan spinning for no reason at times but mistook it for my CPU fans which i cleaned multiple times. It turned out to be my graphics card fan i was hearing.
My Mac Pro is now back to being the silent beast it once was and to the person who said the dust issue is nonsense, i say to you that ventilation is key. If we as people cant breathe, we die. The same goes for a computer.
I normally dont post in forums and this may or may not be your issue but hopefully this helps someone and saves them a few grand.
Good luck guys (and gals) and I truly sympathize w/ what your going through.
It started with my machine before Lion.
BTW, since the cleaning and dusting and reseating at least a year ago, mine has been ok. I still keep it off of auto restart just in case. My USB ports are dying one by one and if I leave something plugged into one of the bad ones the thing will stick half way up on boot (I'm guessing I need a power supply), but otherwise, we're keeping on keeping on. (knock on wood).
Thanks for the feedback i blew my Mac Pro out with compressed air and cleaned the video card connector and ram connectors with a product called Deoxit and pro gold connector enhancer. it booted up first time and so far so good. if you google these products you should find them easily. i had a simmilar problem with some audio device and it fixed it.
if you dont her from me again Problem solved. (thanks again)
Hello to all,
since a few days, I can add my MacPro to the list of spontaneously restarting Macs.
Haven't gone through the whole thread so far, just wouldn't think that it is caused by a overly dusted Gfx-card as I carefully clean my Mac once a year.
I had this behaviour once while the Mac was rendering a 3D-graphics and thus hours of work were wasted. Second time was shortly after waking up from sleep and starting Safari.
As OSX did not generate a crash report, I had a look into the Apple System Log (ASL) protocol and both times I found an entry related to Notification Center which correlates pretty good with the crash time:
2013-01-05 15:02:11 +0100 NotificationCenter: Unable to simultaneously satisfy constraints:
"<NSLayoutConstraint:0x7f86d2e0fe90 H:[NSView:0x7f86d2e0f6e0]-(0)-|(LTR) (Names: widgetView:0x7f86d2e0f390, '|':widgetView:0x7f86d2e0f390 )>",
"<NSLayoutConstraint:0x7f86d2e0f9b0 H:|-(100)-[NSView:0x7f86d2e0f6e0](LTR) (Names: widgetView:0x7f86d2e0f390, '|':widgetView:0x7f86d2e0f390 )>",
"<NSLayoutConstraint:0x7f86d2e10290 H:[NSView:0x7f86d4522ba0]-(0)-| (Names: '|':NSView:0x7f86d2e0f6e0 )>",
"<NSLayoutConstraint:0x7f86d2e10230 H:|-(0)-[NSView:0x7f86d4522ba0] (Names: '|':NSView:0x7f86d2e0f6e0 )>",
"<NSAutoresizingMaskLayoutConstraint:0x7f86d416b4c0 h=--& v=-&- H:[widgetView(385)] (Names: widgetView:0x7f86d2e0f390 )>",
"<NSLayoutConstraint:0x7f86d4522c40 H:[NCSwitchButton:0x7f86d45263a0]-(>=9)-| (Names: '|':NSView:0x7f86d4522ba0 )>",
"<NSLayoutConstraint:0x7f86d45234e0 H:|-(35)-[NSTextField:0x7f86d4513110] (Names: '|':NSView:0x7f86d4522ba0 )>",
Will attempt to recover by breaking constraint
Set the NSUserDefault NSConstraintBasedLayoutVisualizeMutuallyExclusiveConstraints to YES to have -[NSWindow visualizeConstraints:] automatically called when this happens. And/or, break on objc_exception_throw to catch this in the debugger.
Has anyone observed similar? Does anyone know, if this could be the cause for the simultaneous restarts?
(Of course I'm no programmer, so this could just be an coincidence and of course I wouldn't exclude the possibility of a hardware defect).
At least, I now excluded every application from the Notification Center and will observe further on, but it would be interesting if anyone found a similar entry in ASL.
[Specs: MacPro 8-core late 2008, aka 3,1; 8800GT; OSX 10.8.2]
hm, well - not exactly the answer I was hoping for
But you might be right: SL was the most satisfying OS during the last couple of years - at least on a working machine like the MP. Lion was pretty much disappointing and I was shortly before downgrading again, but waited for ML for its upgraded Gfx drivers and the possibility to pretty easily use PC Gfx cards right out of the box.
(I am hoping to get better performance in several applications that I use, but still haven't gone that route).
ML offers in deed features that don't seem very appropriate for a computer that is primarily a workhorse and those seem to offer a lot of unnecessary sources of errors.
Besides the rebooting issue that hit me lately, I'm experiencing some other minor flaws and was also assuming in the direction of incompatibility issues between MP3,1 and ML or errors that might have cumulated because of OS upgrades instead of doing clean installs each time (what was my standard routine prior to SL).
But because of the above, I will stay with ML for a bit longer but will most likely do a clean install when v.8.3 is out…
Mac Pro 2009 here. I think I solved it for my particular case, which appears to be due to static electricity building up in the rug on which my Mac sits.
Background: I've had random restarts for months but it recently got more frequent - multiple times per day, sometimes the fan was full blast on restart, etc. Sometimes simply brushing my foot against it could cause a restart. Thought there could be no way it was static though since, by design, the Mac should dump any static to ground by design (really, any hardware should do this).
However, the Mac is sitting on a rug under my desk, it's the middle of a dry winter, and I have a radiant heater under there. In other words, it's very dry. And between that and me shuffling my feet around on that rug, it's very easy to build up a static charge. I'm guessing it would build up enough over time to give the Mac a shock.
Solution: Isolate the Mac from the static electricity building up in the rug. Specifically, I put paperback books under the front and back of the Mac Pro to isolate it. Since doing that, I've had no reboots for the past week.
Really thought the power supply was going but it was as simple as this.
In March, 2012 I was having the same issues with the Mac restarting (see my post about this here: https://discussions.apple.com/thread/2098873?start=270&tstart=0). A new power supply unit and graphics card were installed and it has not missed a beat until yesterday when it restarted once and then this morning it restarted twice in a row.
I've decided to bite the bullet and buy a new one, as it is now 5 years old but if anyone has any suggestions on what else I might do, it would be apprecaited. I've tried most of the suggestions on this list but thought that it had been fixed in March 2012.
Kurok, I did the same. My computer died last Monday during a deadline job. Luckily, my old G3 started. To buy a refurbished motherboard for a 3.2GHz mac pro desktop was abougt $800 and then again, maybe it was the power supply. I hate to say it, but the next one after this one will be a PC. My husband bought a PC the same time I bought this last mac and uses it in his office everday and leaves it on every night. The thing is still working like a charm. Plus, he still runs some of the older OS's on the other machines in his office. Macs are too expensive and too obsolescent as far as the parts after a few years. I could have bought 2 PC's for what each one of these machines cost me. Not worth it anymore, for me. Photoshop and Illustrator will work just fine on a PC.
Take it as a warning that something is starting to go. I cleaned mine out and it ran flawlessly for almost a year. Then it died. Please, back everything up often, they're on their way out.