8 Replies Latest reply: Jan 21, 2013 8:29 AM by Steve Holton
Steve Holton Level 4 (1,025 points)

The symptoms:


  1. Running normally, screen goes black
  2. Fans(s) do their 747 takeoff roll imitation
  3. Won't wake up (shouldn't have been sleeping at the point this happened)
  4. Force power off
  5. Attempt re-boot, black screen no sounds except fans take off again after a few seconds


Open it up and find 2 of the 9 red LEDs on the motherboard under lower memory tray are lit up.

Specifically OT1 and OT2 - pretty obviously Over Temp Indicators.

They stay on when power is off, only go out when power plug removed.


If you remove the plug which turns them off, then re-insert they stay off until you power up.

Then the 2 LEDs come on and the fan starts and the 4 LEDs on each memory tray (DIMM1,2,3,4) flash continuously and nothing happens.


There is nothing hot about it.

When it happened was doing normal things - monitoring temps in the recent past  has shown everything to be fine

Let it "cool" for an hours no difference.


In the process I re-seated all the memory - no effect.

I see no dust in any of the visible areas.


One other thing that may be a clue, it has recently occasionally powered itself up spontaneously when turning on the power strip that supplies it.


I can't think of anything that I can do.


Don't suspect the Genius bar has anything to add beyond putting in the shop.


Any thoughts?


If it's the mother board (but no the processors) any idea the magnitude of the cost of replacing the MB??

Mac Pro, OS X Mountain Lion, MacBookAir,MacBook,iPad
  • The hatter Level 9 (60,930 points)

    No idea what or how but seems strange, been seeing near identical like your post cropping up every weekk from 2008 owners. They had trouble early on (first two months) with freeze on wake from sleep for one thing. There were SMC and EFI updates, later models had that rolled in and improved motherboard. (One reason to hold off for first 3-4 months for revisions based on early reports to be fielded).


    You or someone else with power strip, my suggestion is avoid those things and get a solid 1500VA UPS w/ Sinewave, if nothing else but I thiink they improve and prevent by providing the PSU with good clean power all these 4 yrs you've had yours or the 6 yrs I've had mine.


    http://www.amazon.com/CyberPower-CP1500PFCLCD-Compatible-1500VA-Tower/dp/B00429N 19W/


    Other than reset the motherboard SMC and playing around with Risers and DIMMs and running AHT, even try running 10.5.x off your OEM DVD on a freshly iniitialized drive - just to see and test it works with the original OS! worth a try to have clean bare hardware and OS.

  • Steve Holton Level 4 (1,025 points)

    Thanks for your reply.

    It doesn't get far enough to do anything like boot from DVD, or open DVD tray holding left mouse button on boot up.

    The flashing LEDs on the memory trays indicates to me it hasn't got far enough to locate and configure all the memory.

    It flashes the LEDs for all 8 DIMM slots. I only have 4 populated. So I'd guess the trays are saying that they are not yet configured.


    I will try removing unnecesary stuff like SSD PCI card drive, eSATA adapter etc and see if that helps.

  • The hatter Level 9 (60,930 points)

    If you can get one pair of DIMMs working with just one Riser.


    http://www.dvwarehouse.com/Apple-Memory-Riser-card-for-Mac-Pro-First-Generation- 922-7695-----NEW-p-37247.html




    you don't need any hard drives if that helps - AHT just needs "something"


    Amazon has 2x2GB $54, 667MHz work fine and can't notice 4% difference.



    I don't know of cheaper - outside used & ebay market.

  • Steve Holton Level 4 (1,025 points)

    I've found it!


    The OWC PCIe SSD drive that was my boot drive was the culprit.

    I removed all unessential internal PCIe and external devices and it booted.

    Adding back just the SSD caused the problem.


    I can understand why a bad card/device could cause it to fail at boot time - but with Over Temp indicators - weird.

    Installed/attached everything else and it booted several times and up for 30 miuntes now.

    Keeping my fingers crossed!

  • The hatter Level 9 (60,930 points)

    you are neither the first or last w an ssd issue.

    I'd look into firmware for one thing, just like firmware affects your PCI contrller would.

    you must feel like you're floating after looking into dark pit of *** happened.


    system hardware profile was nice to have, profile should have complete list


    so you got this right after...? upgrade to 10.8.1 from 8.0, or from 10.7.4?.

  • Steve Holton Level 4 (1,025 points)

    The hatter wrote:


    so you got this right after...? upgrade to 10.8.1 from 8.0, or from 10.7.4?.

    No been on 10.8.1 for awhile, just happened....

    Will see what OWC says.......

  • Bradley Brown Level 1 (0 points)

    Just adding to the record. Your post helped me solve my issue.


    I experienced the exact symptoms on my early 2008 MacPro 2.8. Detaching my SSD nor any of my 5 internal HDs solved the problem. Disconnecting my external Samsung USB-connected Blu-Ray writer returned things to normal. The OT lights and failure to start must be related to some improper signal that is encountered while the computer searches for startup drives. I'm just surprised it happens the moment the computer is powered on and not 1-2 seconds later.

  • Steve Holton Level 4 (1,025 points)

    Forgot to post a follow-up, but OWC replaced the drive and it's been running fine since.