Mac Pro rebooting loop

[fxrtst]

Hello all,

I have an Octo intel core Mac Pro purchased in Dec 2007. It has been running fine no problems until yesterday. It will reboot while in the midst of working and get stuck in a loop from the reboot. The Mac sounds like a broken record on reboot, skipping over and over at the internal chime boot music. It will after several attempts reboot, only to reboot anywhere from several minutes to a few seconds. I've unplugged and rebooted no fix. I had a WD 1 terabyte HD External that I removed, still not the problem, although I do notice it happening (crash reboot) when access any drive including Mac main HD. But, it has also happend when I am not in the room. There does not seem to be a pattern to the reboots. Is/has anyone experienced this? Any ideas as to the cause. FYI, I was using Final Cut Pro 6 the first time it happened, but will happen now without it running.

Thanks in advance.

Will

P.S I have Boot camp installed and tried booting into Windows..after several failed attemps at getting to the multiboot OS start screen after auto reboots, I managed to get there. Only to have the reboots happen there as well. So it sounds more like hardware than software?! Is it possible for the system to overheat and reboot? Its not impossibly hot, but we have had record temps here in LA, aroun 101 degrees and the house was about 90?! Just a thought.

 

[Transeau]

it sounds to me like a failing hard drive. Can you boot from your install DVD and run a diag? (boot holding 'D' with the DVD in)

 

[fxrtst]

That was my first thought, but Windows is on another HD and when I booted from there, I had the exact issue as on the Mac side. I am thinking now that it may be some kinda power issue, like something is loose and the power gets jiggled, although I checked the power cord going in to it and the wall all seems well. I will try to boot from the DVD.

 

[fxrtst]

Diagnostic ran on HD while steady, not rebooting....says HD is fine. Tried the DVD and booting to hardware diag, but hangs when doing first test on RAM..tried many things, but refuses to do anything but hang. I did a Apple +S and did a fsck -f, fixed some file structure...still unstable and after reboot..I am assuming my reboots are now some form of crash, as when I was in Apple + S environment..everything was stable during its checking. I really do not want to do a re-install of OS only to find its a hardware issue....lose all my work..wish I had another hard drive to swap out to install OS to and see if its the problem.

 

[Transeau]

OKay, next would be booting with the case open, checking the memory LEDs. You should have NO LEDs lit on the memory cards.

Also, get a flashlight and a non-metallic... something... long...
There is a "DIAG" button on the mainboard near the upper memory card.
Press the button and a series of lights will light up. You should see 1 orange and 2 green. Press the button and make note of which ones light up.

If you have more than 2 FB-DIMMs, you can pull them out and try booting with various combos of two to find out if it's ram.

 

[fxrtst]

OK, no memory cards are showing LED's lit. I am having trouble locating the Diag button in the location you are refering to. Is there a link to a picture of the button I am trying to link too? Interestingly, the issue has stopped for now, but lost my whole Final Cut project, clips destroyed and project is pretty messed up. I assume I have trouble with files on both HD's. I really would like to continue to trace this out incase it happens again..I lost a days worth of editing.

Will

 

[gmillerx]

Same problem -- reboot loops

1. octo-core, same setup; Vista64 in boot camp; all software current; 13Gram; 3.5TB; X1900Xt

2. i reset NPROM, SMC

3. WIndows diags says memory is ok; AHT in extended test says everything is ok

4. continually reboots at greyscreen (YOur mac needs to be restarted); and dies in Vista safe mode at crcdisksys (but AHT didnt skwauk)

5. Boot from Leopord "D" option show MAC, Vista, LeopardDVD--but gave me 'grey screen of restart' when i selected Leopard Install disk (hoping to run Disk Utility from it to check the system drive).

sounds like power shut-off glitch, or a boot prom error? i figured AHT would let me know if the drive was bad, and install-from-dvd should at least have STARTED and not crashed...

really stuff--cannot afford to lose all the application software (that uses install keys/counts)... dead in the water... no idea...?

[first started after i updated Ati drivers, aand again after i tried new Radeaon 4850s...went back to x1900xt thinking IT was the problem with restart-loops, but the problem has reoccurred when i went back to the x1900xt... after running fine for a couple of days... very sudden, suspicous.]

glenn miller (and this is my first mac in 15 years....sigh)