Q: My Mac Pro spontaneously restarts

I'm pretty conviced my restart were caused by bad ram, I pulled 2 ram modules that were faulty (indicated by the led's on the memory boards)

I thought I had solved the problem back in August by reseting the System Management Controller (SMC), zapping the PRAM, and re-seating my ram modules etc,

and it seemed to be more stable, for some reason I didn't check my ram for faults at that time, so

I decided to check my ram and discovered two fualty ram modules

I have had 4 weeks of trouble free operation since pulling the faulty ram

maybe it's a combination of things, who knows? but my system seems solid at the moment so I'm not complaining

good point Leon, lets keep the thread on one specific problem "early 2008 Mac Pro spontaneously restarting" plenty of room to cover other models with new threads

hmmmm? just checked the original PO's post and he doesn't specify which computer he has this problem with?

in fact he has "MacPro G5 (aluminum)" in his tag line (a computer which doesn't exist!) so this thread is already in kitchen sink territory

Thanks, that is at least somewhat comforting.

How long has it been since you did that?

I am currently having a bit of luck.  I set the Energy Saver preferences so the computer never sleeps (I still have the defaults set for the display and hard drives to sleep).  Since then, almost two days so far, no shutdowns, and befoe the change it was getting to be at best a few hours.

I did that because I had noticed it seemed at least some of the shutdowns came at times I thought the computer would have been waking up.

My theory at the moment is that maybe wake up pulls extra power or puts an extra load on the power supply and that is enough to drag down a marginal power supply to the point it triggers a shutdown.  Pretty doggy theory, but so far so good (knock on aluminum).  If there is anything to that it would seem the power supply is going marginal and it is just a matter of time until that is not enough to keep it out of trouble, but I will take what I can :-)

I do wonder about the power supply in a Mac Pro getting to a state like that.  So far it looks like the Mac Pros have 980 watt power supplies.  That is pretty big and I wonder how/why it could degrade far enough to cause this given the fairly moderate configuration I have.  But I do note the mentions of display adapters in this thread and I think they are pretty heavy power consumers.  Also, when I added and replaced disks I went for faster rather than lower power so they may be pulling some extra power.  And I did add memory.  Not sure what its power consumption is, but looking in iStat Pro the temperatures it reports in the memory area seem to suggest that uses a good bit of power too.

Wait and watch...

Hi Leon,

No you are not being rude ( and I wouldnt mind if you were!).

What was interesting to me reading this thread is that the spontaneous restart problem seems to be persistent across models of mac right up to the current ones. It may be that there are multiple reasons why the mac pro's restart so easily.

One thing for certain is that all the reading I have done over the years has never led to any kind of fix.

C'est la vie I guess.

After replacing 2 sticks of bad RAM my Mac Pro is doing ok again!

Your post caught my eye since I had a similar problem a while back with my Mac Pro 3,2 (early 2008). The solution: carefully cleaning the inside of the computer where a LOT of dust had accumulated. I haven't read all the posts in this thread, so I apologize if this suggestion has already been made and tried. But if it hasn't, I highly recommend it.

I had all of the issues mentioned in this post: random restarts on a 2008 MacPro3.1 3.2 GHz tower. Sometimes several in a row. Sometimes the computer would restart and before loading the Finder would restart again, several times in a row, and like others the restarts seemed to cluster around a certain time of day (in my case the late afternoon). I cleaned the inside, reseated the RAM, reset the SMC and PRAM. It still did it. When I put it into Safe Boot it wouldn't do it, but who can work like that? The last two things I did were unplug my iPhone and disable computer sleep. It's been nine days since I did that and it hasn't spontaneously restarted since. Personally, I think it's sleep. I urge anyone with this problem to try this first.

Something odd happened so my last post was made without having seen many of the recent comments after my first one, so it is a little out of context.

Based on my observation I think it may be helpful for posters to note if they have restart after power failure set.

In my case it is looking like the problem is really that the computer was restarting after it thought there had been a power failure, rather than any sort of mysterious spontaneous reboot.  By turning off automatic reboot aftrepower failure I am able to distinguish the two and identify the real issue in my case is that the machine apparently acting as if it is seeing a power failure.  That might be from an actual power problem coming into it or perhaps it relates for example to the machine's power supply.

Four days of observation indicates that when I have sleep enabled it happens, and when I do have it set to never sleep it does not happen for my case (at least so far).  That strongly hints at something to do with sleeping - quite possibly in my case when it wakes from sleep.

Question:  for those who think bad memory is involved for them, what indicators are you using?  One would be just finding that replacing memory made a difference, but is anyone using other indications?  I don't know where there is documentation on ways to check memory.  At one point a little while back (not directly connected with this power/restart issue) I noted mentions of correctable ECC errors in the About This Mac / More Info / System Report / Memory page (I replaced the problemmemory module and that seems to be resolved BTW).  I am also curious about an early reference in this thread to LED indications.  Can someone give or point to information about that?

One other question - When it comes to the thorough cleaning out of dust, etc. are there ways to open the machine up further (early 2008 version) beyond taking the side door off and possibly pulling out disk drives and memory boards?  There seems to be quite a bit of the interior that is not easiely accessable for checking or cleaning.

Been having the same kind of problems. Maybe not as long but still as annoying. I reset my energy saver. Going to see if that does it.

Good luck trying the don't sleep and don't autoboot after a power failure preferences.  Please post back here how you make out.

Don't autoboot after power failure helps isolate and define what is happening (seperates response to a perceived power problem from some sort of unexplained rebooting for no apparent reason).

I do suspect that don't sleep is basically a side effect rather than an actual cause source.  That is the actual problem may be transient loading on the power supply during wake up or some such.  (I do have to note however I am seeing my machine pulling 200 watts for normal operating out of a power supply that is apparent rated at more than 900 watts, so the chances of it being overloaded by anything that the machine does seem pretty remote unless the power supply is really degraded or malfunctioning somehow)

In any case, anything that helps or even just changes the symptoms is worth while being aware of and sharing here. 

My early 2008 Mac Pro had several of the following symptoms that have been mentioned in this thread: 1) spontaneous deaths and restarts in the middle of a session, sometimes several in a row before managing to stay booted and working; 2) failing to awaken properly from sleep, requiring a hard reboot; and 3) dying at some unspecified point while asleep - that is, when I return to the sleeping computer, the power light is full on (not pulsing as it should be) and the computer is effectively useless, also requiring a reboot.

About a month ago I pulled the two memory cards, cleaned them up as best as possible, and pulled and reseated all of the RAM modules. Since then I have had no problems <*crossed fingers*>. So in my case I think it was a RAM seating issue, and I fervently hope I've solved it. To all those who haven't tried this, I strongly suggest you do so. For those who have tried it and continue to have problems, you have my sincere sympathy - I know how aggravating the issue is.

Anyway, just thought I should follow up on this since I had complained earlier in the thread about the problem.

Okay, I'm jumping into this thread now too. I'm another one with an early 2008 model Mac Pro doing unplanned restarts. Started a few months ago. Sometimes it would restart even while restarting. Sometimes the DVD tray would eject while restarting. All very strange and annoying.

I was once able to reliably trigger the restarts by running an Office 2011 updater at the same time as Sophos was auto-updating. Uninstalling Sophos did not stop the restarts.

At first I suspected a hardware issue so I took it in for repairs and the shop did a hardware test and found a faulty hard drive. They replaced the hard drive and all was good for about 3 weeks and then it started spontaneously rebooting again.

The shop then thought firewire hard drives plugged into it could have been causing it, but unplugging those drives did not fix it.

The suggestion I've read in this thread which has worked pretty well for me so far has been to 1) zap PRAM, 2) reset SMC and then 3) reset defaults in energy saver prefs. That combination bought me a whole wonderful month of stability and then it just did an unplanned restart half an hour ago.

In response to BobHassinger who suggested some transient loading on the power supply during sleep, unfortunately that would not explain my Mac's issues, since it will sometimes restart before the computer has had a chance to sleep, for example a couple of minutes after turning the computer on in the morning.

I'm now going to try disabling computer sleep altogether.

By the way, I had a hunch the machine was going to 'spontaneously' restart again this morning because the DVD tray ejected while it was booting up this morning, and that was something that often happened during the unplanned restarts for me. There are other suggestions here I want to try too, but I'm keen to try one at a time to see if it narrows anything down. So far the only real lesson I think I have learned for certain is to keep saving my work regularly.

(Early 2008 Mac Pro, 2x 2.8Ghz Intel Quad-core Xeon, 12 Gb RAM, with a Wacom tablet, 30-inch cinema display and a Samsung second monitor plugged into it)

Ugh. Mac Pro 3,1 here. Following up on my issue, which may or may not be related. Short history: Lots of restarts. Reseated all RAM. Stability for nearly a year. Random restart a few weeks ago. Yesterday, I happened to notice in System Profiler that I was "missing" 2 gigabyes of RAM because RAM in Riser A, DIMM slot 2 had "failed." This was RAM Apple installed at the factory. Hynix 1GB modules. I pulled those and moved my third party RAM into the open slots. I'm down 2 GB, but I'm hoping this had something to do with my particular issues. But as we all know by now... only time can tell with this random failure stuff. I'll report back any new flameouts.

The latest suggestion from this thread which I tried was to set Computer sleep to 'never' in energy saver prefs and my Mac (early 2008 Mac Pro) has not done a restart since then. Playing with those energy saver prefs does seem to somehow improve things so I'm suspecting something going on there. Or at least in my computer it does. Also, perhaps completely irrelevant and unrelated but I installed the latest drivers for my Wacom tablet. Anyway, I've had no unwanted restarts since doing those things and I'm just hoping things stay that way.

(Early 2008 Mac Pro 2x Quad Core, 10.6.8)