my mac pro early 2009 keeps restarting with an unknown error

Hey SergioMacProUser,

I understand that your Mac is crashing. I would check out the troubleshooting steps in the following article, specifically the "If the issue occurs in various applications, or in Mac OS X" section:

Mac OS X: How to troubleshoot a software issue

http://support.apple.com/kb/HT1199

Sincerely,

Delgadoh

Pull the system drive. Or try command R to get into Recovery Mode (or use Option key)

Try your backup clone. If you don't add that to your to do list and for now get out your OS X Install flash drive you saved and made or your DVD if you are on Snow Leopard.

System is one thing. CPU refers only to the processor(s), not the disk drive which sounds to be corrupt, not the gpu which also could be an issue on yoru Mac Pro model (tell us - 2008 3,1 or whatever it is).

Panic or Prohibitory sign could be further hardware issue, or just need to see if it will try with no hard drive and look for "?" a system to boot from.

Reset SMC also in cases like this.

I have this problem as well. Same tower, Snow leopard. I gave tried all of the recommended remedies. I have upgraded to Yosemite. This problem still persists. I have taken the tower to an Apple certified dealer who has done extensive testing. The problem persists. If you have had any success, I would be glad to hear what you have done. This is my production machine and the problem is very frustrating.

If this problem occurs across multiple versions of Mac OS X, you may have a Hardware problem. Check for issues using some of these approaches:

a) run Apple hardware test

b) run a temperature monitoring program, look for high temperatures

c) make an appointment at the Genius bar of an Apple Store for a FREE evaluation. No obligation to have them do anything for a fee.

d) Power off and disconnect the power cord. Slide out the processor shelf and wiggle the Northbridge chip. If it is not solid, you have a problem. It is located as shown below on the 2009 throughout 2012 silver towers. The picture shows the processor heatsinks removed, but you need not remove them just to check whether the heatsink is solidly attached.

Thanks for the advice, I've tried all of these things short of lugging the tower a long way to the Genius bar. I have run extended apple hardware tests. Nothing found. I have tested for heat, not sure what excessive heat is: 109 degrees on the CPU AT diode, seems normal when compared to the other hardware temperatures. Powered off and checked the Northbridge heat sink, it is firmly in place. The problem is intermittent, but keeps reoccurring

You can use the Console Application to read out some of the log around the time it does this stuff. If you are the Admin, In Console's search window, type BOOT TIME and it will show you the line where it re-booted. Select that line, then uncheck the search and select up to ONE PAGE of stuff leading up to it for readers to look at, and post it on this or another thread on the forums.

here are some screen shots of what you suggested:

one more

look at the comment at 11:02 from the kernel about excessive wakeups and the maximum number of wakeups. I'm seeing this each time around the restart. Also curious, it's not like a total restrt, it goes to the log-in screen but after log-in, it open all of the programs that were open before the restart. Could this be a clue?