it seems I have a similar problem since this morning... it look like others with the same Mac Pro has this problem too...
1. Just after starting my day, I heard a "click" and suddenly my Mac Pro restarted (well try to) several time on itself . I had to manually push the power button to stop this.
2. After lot's of emotions I started it again... and It finally boot and goes fine for a few hours...
(I quickly run a few backups... and did some hard disk testing, seems fine).
3. it happens again when the computer was "on sleep" as soon as I started it, the problem came again again the same way.
I am also suspecting a *power supply* issue (I never had this problem but I already had to replace the PCI video card on this computer)
I will try call Apple tomorrow to fix this.
Did you get more info since from your side ?
My early Mac Pro has a similar problem. It takes up to 30 reboots to get the start up chord and a steady "on" light. Once working it is fine all day but on the many occasions that it does not start first thing (can take up to half an hour every morning!!!) I get a slow blinking light and a black screen. I have changed the system disk with a clean install of Snow Leopard PRAM, tried disconnecting everything including internal disks, reseated the ram, taken out the PCI cards but the problem continues. It all seems to happen in the first couple of seconds. The fans come on but if the power light is blinking It won't start..however a steady on power light will mean that it will work. Any solutions or known issues?
As indicated in my previous post (for me) my MacPro shutdown/restart after the first 5 min. I deactivated the "energy saving" to prevent suspending activity and it's fine for the rest of the day. To resolve temporarily the next start-up i've noticed that too: if I disconnect the plug before the first powering up, it almost goes fine afterwards without failure.
To me it definitively looks like a hardware problem (a power issue as Macbig said?). Also it seems my main system hard drive is disconnected during this problem, as time machine has to do a "Node requires deep traversal" afterwards too....) I still have a valid Applecare and I'll bring it to a certified apple expert as soon as I've finished my current design work. I'll let you when it will be fixed in the next one or two weeks (I hope).
to rick: if you have a blinking light (which I don't, it just clic/restart) look the following thread too.
I took my computer into my local Apple Store (Santa Monica) and they agreed something was wrong but could not diagnose -- they replaced the motherboard with a new motherboard. This DID NOT fix the problem. The workaround for me -- clunky solution -- Is:
(1) I set the computer to automatically start up at 6AM via the energy saver control panel. It does not do this but "something" happens internally - something gets tripped.
(2) Then, I turn the power ON & OFF at the power strip plugged into the wall before starting. I hear a "click" from inside the Mac Pro.
(3) Now if I hit the power button it starts up. Seems to run normal from there but freezes in SLEEP.
My personal theory is that one of the software updates beyond 10.6.x does not support energy management on this motherboard. Apple is not going to admit to that. What? Give me a new box?
I am still under Applecare...
I have very standard hardware but 3 internal 2TB drives. I have considered it is one of these drives that is not able to negotiate the start-up signalling or to handle sleep. Maybe. I have tried several different brands, they all exhibit the same behavior.
Thanks for your feedback, I still did not have the time to bring my MacPro to a certified expert, I will do it for sure but I need to finish a few works in progress... (I'm doing a lot's of backups then...).
*My actual workaround is unplugging the power cord during the night, and it does not stop and stays on almost ~8 hours or more fine.*
To me, it cannot be the system, I'm using 10.5.8... but I also have 4 internal hardrives, Three PCI cards (display, small eSata controller, and blackmagic video card). I did not install any hardware since one year. So it's definitively a hardware issue, and the way it happen, it is certainly electric (I doubt that it's a RAM issue).
Good luck, I'll keep inform later,
Just looking for other information in the meantime... i've found this:
As I have four of this Samsung HD 1 To, I was wondering about what's mentioned in the middle of the second paragraph:
"(...) +Often bad power supply unit combined with power streak is enough to burn spindle driver chip on the electronics and make data inaccessible. Should this occur the computer would reboot itself or shutdown completely, you would normally notice acrid smell and smoke and the drive will no longer spin up.?+"
But as far I'm concerned, I don't have, smell, smoke or any data problem (yet). Btw it just "cut off" again after 5 hours of Power ON during an After Effect Render...
I also have recently got this problem. Press power ON . and the Click sound and goes off. sometimes starts booting up for longer but then Click and OFF again. Then sometimes works for few hours and Click Off again.. Hardware tests (extended version) says "No trouble found". ha!!!
More odd thing today was when pressing "Build and Run" on XCode would keep shuting the computer down with that CLICK.. so I would restart (it restarted well today) . but again same with that... happened 10 times.. so looks connected when processor was making some effort. i just don't have an idea.
Computer is also a Mid 2008 Mac Pro...
Anyone found any solutions or diagnosis of what is going on...???? Gone though quite a few forums... clean this, change that, and for some it works, for others it doesn't .
I will also get this computer to a repair person.. and if they find a solution.. will post what i find.
back to working on this slow old macbook and backing up everything 5 times a day.. just incase.
Yes IN THEORY this behavior is what you would expect if the battery on the motherboard was dead or there was some problem with PMU management (I have tried resetting PMU both from front of computer and directly on motherboard -- no luck, does not resolve issue.) I encourage others to try a PMU reset as a solution (Google Apple PMU reset) .I have tried a new battery as well. I have moved RAM around and tried a lot of RAM configurations, including minimal OEM RAM. No effect. Does not resolve the "on button" problem. I suppose the solution could be an entire new power supply but that seems odd since the power supply does work, just does not turn on reliably without the mysterious click. It is 3 yrs old... would not surprise me if it had a limited life. That "click" noise is an electronic relay of some type, that much is almost certain. Bad relay?
Message was edited by: waltmorton
I will see if removing USB make a difference. This morning its starting up fine and so far its working, so am waiting for the issue to return ( ) . Was surprised with google searching just how many many people have / had this issue, and for different models going back many years, and i also found some quite identical issues when search "random shutdown" in Youtube.