Q: My Mac Pro spontaneously restarts

Thank you CDPlayer. I didn't know about that.

Ok--here's a further update to my original post on 11/11/11. My cure is continuing to work. But I just learned something new.

The problem was not bad RAM, as I had thought, but a bad riser card in slot B. (THe problem could also be the slot itself, but a tech tells me it's more likely that the problem is the card.)

I know this because I just put the RAM modules that were in riser B (but not showing up on System Profile), into riser A. And they're good! So I'm back to 3GB total, which is adequate for my needs.

So in my case, the diagnosis seems pretty clear: the auto-rebooting syndrome was caused by a bad riser card in slot B (or conceivably, the slot itself is bad).

Anyway, I've had no problems for a full week now, so I'm feeling optimistic and crossing my fingers. Thanks to you guys who contributed to this thread for your help!

I will be more convinced after you put in a new riser card, check that the ram works and have no problems for a serious periode of intensive use, a month for example.

I had the same problem: RAM not showing up, same RAM showing up when placed in different sequence.

It could be the riser, but it might just as wel be a problem with a RAM module working fine when placed in bank 1 and not in bank 2. Testing memory is very complex. It could just as wel be in a different part of the hardware.

I have received a lot of help through various forums, and I thought I would add my experience to this one in case it might help someone who has had similar problems. I found this discussion in a search for my original problem. About a month ago I got up, tried to start my old Mac Pro Intel--I think 2006--2.66 ghz Dual Core Xeon. Instead of starting, the white LED came on, immediately went out, and then about two seconds later, it would try to start again. The fans tried to start up, but quit. Thus began a long series of Internet searchs and attempts to fix the problem.

After taking out the power supply and cleaning it thoroughly (as someone had suggested), I thought the problem was solved. Oh, I also took out all extra RAM, reseated all RAM, checked all cables, cleaned off CPU, video card, took out all of the hard drives, started up off of various disks and systems (I had just installed Lion) and replaced the battery. Nothing seemed to work consistently. Also, the computer stopped sleeping.

So, after all this and many startup attempts, it worked. Sleep, though, was sort of strange. There was a long pause and then the light would pulse two or three times and then go off. On wake up, which only worked if I pressed the start button, there would be a dotted progress bar for a while and then it was back to normal.

Another symptom during all this was a Console message of "Sleep Failure Code" with various numbers that meant nothing to me but might to a hardware expert.

ANYWAY...I was away for a while and came home, and it all happened again. This time after various unplugging and hard drive removal, it went through the startup process a little more and then died. It did this several times until the hard drive got corrupted. So I unplugged everything again, rebuilt the hard drive from a back up, tried many more times, and it finally started--but it no longer slept and I was getting sleep failure codes again.

So I ordered a new power supply and installed it today. It is like a different computer!

I write all this at length because it would have been nice to know that a power supply can cause all these problems. I don't know how--maybe the "idle" voltage died or was shorting out. But, it really affected a lot of things. The fans are running quieter, sleep is back to normal (with the pulsing LED and keyboard wakeup), shut down is faster. I never would have thought a power supply would make that much difference.

So all of you who are having all these problems might try a new power supply. I have read that it doesn't fix everyone's problems, but it seems to have fixed mine--at least for today!

Prices are quite variable, so shop around. I paid $200 for mine and saw them for as much as $550. Ebay is a good place to check as well, but I passed on a used one because I didn't want the same problems. This one is a Revision 1. My old one says Revision 0.

1) I promised to get back at this: Disconnecting my LG Blu-ray burner didn't solve my occasional Mac Pro sleeping / crashing problems.

2) @dwight w: Did you install the power supply yourself? Isn't this hard to do?

Leon,

I had also heard it was difficult--and you had to reset the fans or something and all sorts of complex stuff.

I had no problems, and it was quite easy. Maybe later models are more difficult?

The screws are "star torx" or something like that, but a small hex wrench works.

Here is a video:

http://youtu.be/6lOzC3ovhDk

I have an early 2008 Mac Pro (no surprise) that's had the same random repeated restart issues for six months that I've ignored. It's only done it when not being used hence I've ignored it, and have instead listened to it beeping every fifteen minutes or so. No problems during use. But then suddenly it went into wildly rapid restart mode so that I couldn't install the Snow Leopard that I had beside me in an attempt to fix the issue. Then it died completely. Dead as a dodo....not a flicker. Eventually after much cursing and unplugging I put it in the hall to take to Apple. Three days later I plugged it in just before I left and it worked!

I immediately switched off energy saver and it ran for two weeks. Then I switched on energy saver. It hasn't run since. Nothing. I've tried replicating my technical fix ie unplugging and a couple of bumps to no avail.

So that's what happens in the end everyone. I'm taking it a Genius bar next week where either it'll work perfectly or it'll need a hugely expensive logic board that'll work for 366 days.

I wrote in a while ago about my success with turning off Energy Saver and cleaning out the box and reseating all the RAM. That was several months ago and the computer has been running fine. Until recently. A different kind of annoyance started where the screen would suddenly go black. The comuputer was running fine, because I could access all the internal volumes from another computer on the network, but I would have to hard restart it to get the screen back. As it got progressively worse, the computer wouldn't run for more than five or ten minutes. (For the record: 2008 Mac Pro 3.1, 3.2 8-core with ATI 5780 and an 18 gig mix of Apple and OWC RAM.) I figured it was the video card, and since it had worked so effectively for the problem that is the subject of this thread, I shut the machine down, pulled the cords, opened it up, blew out the inside, pulled the video card (and that card is a pain), blew that out, reseated it and restarted it. Voilà! Two days no black outs, from not working at all to working fine.

The reason I bring this up is I would urge anyone having difficulty with a balky Mac Pro to clean it out and reseat everything that can be seated. This has worked twice for me, in situations that would otherwise require a trip to the Apple store and a couple of days on a bench, with probably an invoice for a new motherboard or power supply. I think perhaps these are finicky little beasts and the above protocol has all the engineering elegance of pounding on the side of a television with the heel of the hand, but it seems to work. At least for me.

I appreciate the effort but I have about the same machine and ten or twenty times reseating RAM and daughter boards while I was testing didn't help at that moment (half a year ago or so). Meanwhile memory and machine are much almost stable, without a reasonable explanation.

I understand the motherboard or power supply could very wel be the problem, but which one is it? Even if I'd replace them myself, it would be going in the direction of the (total loss) value of the machine..

I don't even know for sure it's hardware! But if it is, it will not be solved by a slap of the hand. It will only get worse over time. I just work with this machine as long as it will hold, basically what you do with any hardware. I hope Apple comes with a Mac Pro update that's worth it's high price, else I'll buy an iMac this time.

I mean: I'm prepared to pay extra for a 'tank of a machine', but not for a 'machine that tanks' after 2 years.

Bizarre update:

I unplugged the machine (tried for several days before) and put it in my hall overnight. The next day I tried the 'one last time' routine again, and lo and behold it started up. This is the second time this oddball procedure has worked. It remained on long enough for me to install Snow Leopard and I've so far left it running for two days with energy saver turned off. As soon as I'd run all software updates I repaired permissions again (having done this just before the final death throes), and I've never seen such a long list. Interesting.

I'm contemplating installing Lion but will see if it runs normally for a while. There was a strange warning sign that something was amiss whenever it went through its sleep/wake routine.....it lost connection with the Bluetooth mouse until the next forced shut down, so I'll see if that happens again when I next dare to sleep it.

Watch this space.

Ps

I forgot to add that the machine sits beside and has been plugged into a Bose system ie a large amp/speaker/magnet. It's a longshot which no doubt will be proved wrong by a dead MacPro in the morning, but I'm wondering if there's something connected to the fact that unplugging everything in situ makes no difference, yet removing the machine to another room allows a restart. Odd.

Hi, Stephen here. Same problem as every single person in this post.

Mac Pro-Early 2008. spontaneous rebooting and very hard to diagnose. Intermittant problem.

I have found the solution!! Well at least for me.

After taking out drives, graphics cards etc I finally found my solution.

As you all know the mac pro comes with two memory card risers that the dimm's plug into.

I took out the one card completely. Transferred the memory into the other and problem solved.

It was not the memory, log board, processors, pmu, graphics card or any of the above.

It was the the memory riser card.

Machine is running under full load and every different kind of job, no rebooting.

Do yourself a favor and take out your risers and troubleshoot one at a time.

Maybe it works. It worked for me.

Why did apple not pick it up when they tested it? Don't ask me.

Hi Stephen,

Yes, that was precisely my problem and my cure. My last post here was 11/18/11, and my computer continues to run fine.

I had to put all my memory into riser card A. I did that on 11/11/11, so it's been more than a month with no problems.

I don't know if I'm just imagining it, but I may be noticing slightly slower performance. As you know, Apple says to put RAM sticks into alternate risers for maximum efficiency.

Bruce

Hi Bruce

My problem was also with Riser B or 2.

Yes the machine does run slower. The speed at which the log board accessess the RAM is reduced when there is only one riser card. Ideally you want 2 installed. However I must say I think a stable slow machine is better than a fast unreliable machine.

I'm trying to get a new riser card but am now in South Africa and they are trying to source one.

I think I will just buy it online and have it shipped from the U.S.

I am, convinced this is the problem.

On closer inspection I can see that the components on the riser that is not working has a small amount of corrosion on the components on the board. Will let you know if the fix lasts, but I am convinced that we've found the problem.

A Apple techie here in SA who know's he's stuff pointed out that almost always a reboot is Memory related.

That's what made me take the time to diagnose the problem. Start with memory and then move to other issues to diagnose.

Stephen,

Thanks for the reply. So it's not my imagination! My Mac IS running slower. I especially notice it when running Final Cut Pro.

I just saw this dealer online selling a riser card (if this is the right one):

http://www.welovemacs.com/9227695.html

But  I'm wondering if it's more cost effective to buy more ram for the good riser I have, or get a new riser? Did you ask anyone about that?

In riser A, I currently have a pair of 1 Gig sticks, and a pair of .5 Gig sticks, for a total of 3 Gigs.