This started happening to me this morning. My first thought was bad power supply, or possibly not getting good power flow from the outlet or power strip. Reset SMC to no avail, then skimmed through this thread and saw the note about replacing the motherboard battery. I usually do a thorough troubleshooting on something like this, but I need to get work done ASAP, had a CR2023 battery in my bag as a spare for my bike lights. Shut down, swapped the battery (checked for dust accumulation and dirty RAM contacts, clean), and so far am running flawlessly. Fingers crossed.
Mac Pro 2,1
Quad-Core Intel Xeon
Processor Speed: 3 GHz
I've been suffering from this problem for a couple of months now.
Seems to be QuickTime based applications that cause the restart - Final Cut Pro, QuickTime, After Effects. But I've had Cinema 4D up and rendering hard with no issues whatsoever. Not sure if this can point to a problem with CPU vs. GPU?
I've taken the inners apart, dusted, compress aired the internals, replaced the battery on the motherboard, re-seated all PCI cards and RAM - still the same issue.
I'm assuming it's a graphics card issue, but I'd like to confirm that before I fork out for a new one.
I had a similar issue a year ago while working in Apple Color, my displays would go black, the machine was still on - I could access the drives over the network, but I couldn't screen-share it. Luckily I don't do much Color work anymore, but the problem seems to have spread.
Any ideas/suggestions/solutions gratefully recieved!
3GHz 8-core Intel Xeon Mac Pro
ATI Radeon X1900 - (Thinking this is the issue, was last year, lots of dust - overheating!)
CalDigit RAID card
Blackmagic Decklink HD Extreme 2K
As happy as many were to see the X1900 offered 6 yrs ago (Sept '06) it was a dust collector, clogging itself and causing the system fans to run harder... for $250 BTO or even $399... think it is time for ATI 5770 $249 anyway.
Though don't know if it directly or indirtectly is the culprit, all the years of user reports sent in use to really help identify a problem or pattern.
Updating my earlier post. The random restart started happening again after I thought I fixed it with a battery swap. And it was actually worse, I could not get the machine to fully boot at all. I'd say about 2/3s of the time it would not even get a startup chime, the power button would light, but nothing would happen, screen would remain black. The other 1/3 of the time, it would get to the gray spinning gear startup screen (and would chime), but that was it, it would never get any further than this. Not being able to boot at all left me with little choice but to take it in to the Apple Store. They replaced the the logic board (for a cost, it is out of warranty), and when I got the machine back, it would startup fine now. Except that the fans were going full speed. Every time. So we took it back again, they now think replacing the power supply wil remedy the fans going full speed (again, for a cost). And they say a faulty power supply could start making other components falter (logic board, etc.). Waiting to get the machine back and I will update again.
Oh and as for the X1900 video card overheating and making a the screens go black (not shutdown or restart)? I have another Mac Pro 1,1 that has that issue. It's a different issue in my opinion, but if it creeps to the logic board, well then it just gets ugly and difficult to diagnose.
So for me the issue appears to be RAM.
I reversed the position of my two risers and reversed the seating position of all the RAM and the restart problem has gone away.
But, on every other restart/start up, the power light blinks which is a sure indication that there's something wrong with the RAM.
Question is, which RAM modules are fautly or is it the risers... pretty expensive to replace the lot. May live with it until Apple clears up the fate of the Mac Pro.
Anyone wanna buy a ATI Radeon 5770?
My final contribution: I had all kinds of trouble, among that one or two spontanous restarts, but much more, like printer problems, kernel panics, freezes, weird behaviour of software. Read my blog if you're interested. Problem was that the problems didn't appear consequently and only very rarely. After about 1,5 year, I even replaced the power supply because I was convinced that was the only possible source left.
Then I did a clean install / update to OS X 10.7. That was months ago and no problem since. Bottom line: It was a corrupt system.
(Buy a Mac Pro 2008 power supply anybody?)
Short answer: logic board.
Long answer: After taking the semi-fixed (restart issue fixed, fans blasting new issue) back to Apple Store 1, they told us they thought the power supply was bad and would replace it. A couple days later, they said it was fixed. We sent someone to pick it up, with instructions to have them start it up to make sure the issue was fixed. When they arrived, they told our employee it just needed a software update. That's it. And when they were asked to start it up, they insisted on making another genius appointment just to do that. So I instructed our person just to bring it back, because if they hadn't fixed it, I wasn't going to give it to them again anyways (would've been the third time). The work order mentioned nothing of a replaced power supply.
Upon getting the machine back in the office, started up, fans are blasting. Still. And since I had taken our real data HD out and replaced it with a clean 10.6 install HD before I sent it in, I doubted that was a fix. Lo and behold, the OS hadn't been updated at all, it was still clean 10.6 from the disc, no software updates were installed at all. At this point I am frustrated and done with Apple Store 1. They failed. And apparently simply lied to us. Or are incompetent. Or both.
So I take it to Apple Store 2, which I get an appointment at within the hour. Apple Store 2 Genius checks it in, tells me there are really extensive notes from Apple Store B in the system (partially me, as I'd sent notes with everything I had tried before bringing it in), and that they had in fact replaced the power supply. The Genius orders replacement fans and a logic board just in case. Tells me we will only be charged if any of the ordered parts fix the issue (and will refund the original logic board cost if they find it never should've been replaced). They will tear it down, and build it back up to get it fixed. Sounds great. A few days later, I get a call to pick it up. They report that the original replacement logic board was faulty, and installed a second replacement logic board to fix the fan issue. And since we had already paid for a logic board, around $480 I believe, I pick it up with no charge to us.
Machine is now running like a champ, **** it seems even quieter than before. I'm a happy camper.
I should note that timing and logistics is why we went to Apple Store 1 first, its closer to the bosses home. Apple Store 2 is closer to myself, and I have much more experience at this store, all stellar. Oh and Store 1 is 29th St. Boulder, Store 2 is Cherry Creek Denver, so if you're in the Denver/Boulder Colorado area, take note. Cherry Creek FTW.
I had the power supply replaced in the 2008 Mac Pro I was charged to fix on behalf of a client. Based on my gut feeling (Electrical Engineering experience) and the previous posts here. After enough spontaneous restarts, it shouldn't surprise anyone that a side effect of the restarting is a corrupted system software. Now some folks also have other issues, like bad graphics cards. There is the mystery of the riser B connections, but it seems clear the power supply seems to be the only true cause of the problem. Either it's not big enough for the loads or faulty in some other way but sized appropriately. Clearly also the "Geniuses" at the Apple Stores are not in fact geniuses, as in higher than average IQ. Glad the _SYMM finally got satisfaction at Apple Store 2.
I wish I had know there are tiny LEDs on the motherboard that you can use to check for error codes of the power supply before I ordered a new one. Or installed 10.7 first.
BTW the supply is more than capable for the load it gets, specially in my case, since I use only 4 HD's and a NVIDIA GeForce 8800 GT 512 MB.
I understand that people get doubts on everthing. That is even a good thing when you want to find a problem. But the power of the supply and the cooling capacity of this computer is really good. If it's a power or heat problem, it's a faulty part, but it's not a flaw by design.
Well, as promised, I'd come back a few months later to post on how its going. Just to note again, what I did was spray air into my 2008 mac pro and also I removed the DIMM cards and cleaned the contacts. I haven't had an issue since then and its been a couple months. I was having a random restart daily. In fact, I would always just surf the web for the first 15 minutes because it always seemed to happen in the first 10 mintues, and if it didn't, if wouldn't happen all day. Well, since I cleaned the DIMMS and contacts, I haven't had the restart problem. I believe it will start to happen again when they get dusty again, but for now, its been clear over a couple months with no restarts.