# Mac Pro powers itself down at boot



## ilovedmy512k (Sep 27, 2007)

I have a Mac Pro, Mac OS X 10.4.10, w/2 x 2.66GHz Dual-Core Xeon Processors, 2 GB (4 x 512MB) RAM, Western Digital Caviar SE16 500 GB 7200-rpm hard-drive, NVIDIA GeForce 7300 GT 256MB video.  I was working on an Excel spreadsheet with Entourage, iTunes and FireFox open in the background.  I was connected to several network drives.  

The computer suddenly powered itself down.  There was not a corresponding brown/blackout in the area.  The power failure was restricted only to my Mac.  The computer immediately started to power up again.  I heard the chime, saw the gray screen with the Apple logo and then the CPU powered down.  Every attempt to power up gets this same result.

I have tried the following:

-Unplugging power and all peripherals for 60 seconds. Plugging in only mouse, keyboard, display and powering up.  No change.
-Holding down CMD-OPT-P-R at start up.  I hear 2 chimes but then it powers down.
-Holding down OPT.  After selecting Macintosh HD it powers down.
-Holding down SHIFT.  No change.
-Inserting the the Mac OS X install disk and then holding C.  I click through the install screens until it asks where I would like to install the software.  The selection window is empty.
-Removing and reseating the hard drive.

I have AppleCare, so I called Apple Tech Support.  The tech had me do most of the stuff I did above again, then told me I would have to bring it in to an Apple Store.  Before I do that is there anyone who can help?

Thanks!

Gideon


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## DeltaMac (Sep 27, 2007)

Did you try the diagnostics that are on your Restore disk? Boot to that test by inserting the DVD, and reboot while holding the D key. This is same disk that you would hold the C to boot the installer. Holding the D will start the diagnostics on that disk. That may report that there is a problem, but you already know that! 
Your symptoms sound like a hardware failure. You need to have someone do a 'hands-on', and check your computer with the diagnostics that the tech at the Apple store will have.


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## ilovedmy512k (Sep 28, 2007)

DeltaMac said:


> Did you try the diagnostics that are on your Restore disk?



Thanks for the suggestion.  I ran the diagnostics (basic and extended) and both tests found no trouble.  I ran Disc Utility > Verify on my hard drive and got an "Invalid Sibling Link" error.  I tried to repair the volume with DU but kept getting the same error.

I found a tip here  here about correcting the "Invalid Sibling Link Error."  The first time I ran fsck_hfs -r it came back with "The volume Macintosh HD could not be repaired after 3 attempts."  Then I ran fsck_hfs -fy.  There was an Invalid volume file count and Invalid volume directory count.  It repaired and rechecked the volume and said the volume was repaired successfully.

I rebooted and WOW!!! everything is working!!!  Now do I need to be concerned about the health of my volume?  Will this problem occur again because of something I'm doing with my machine?

Thanks!

Gideon


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## Kees Buijs (Sep 29, 2007)

ilovedmy512k said:


> I rebooted and WOW!!! everything is working!!!  Now do I need to be concerned about the health of my volume?  Will this problem occur again because of something I'm doing with my machine?



Either this is a glitch (one time only thing) or the harddrive is bad and looses some information at random. If you have only a short period of warranty left, maybe consult an authorised dealer for how to procede (what if the problems occurs a couple of weeks after warranty expires). If the period is still long, make sure to have good and regular backups and wait and see.

This can always be caused by something you did, but this happens only rarely. In that case it is the trick to find out what is you are doing and stop doing it. Backups are then certainly the biggest issue to handle to prevent a major data lose.


Good luck, Kees


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