Mac Pro 2006 CPUB FAIL

Discussion in 'Mac Pro' started by andy2000, Dec 29, 2010.

  1. andy2000 macrumors newbie

    Dec 29, 2010
    I'm trying to repair a 2006 Mac Pro which I bought cheaply because it wasn't working. It has a pair of 5130 CPUs which appear to be original.

    When turned on, the sleep LED lights up, and the fans spin silently, but then the CPUB FAIL LED lights up. There is no turn on chime, or any other sound from the speaker. It will sit there like that for as long as I leave it turned on. Everything seems to be pointing toward a bad logic board, but this is my first Mac Pro, so maybe I missed something.

    When I bought it, it was missing the RAM and video card. I bought a pair of 1GB Samsung 667MHz FB DDR2 DIMMs, and I have them both installed according to Apple's instructions. I flashed an ATI HD3870 with the Mac and PC 3870 firmware, and confirmed that the video card still works in a PC. For troubleshooting, I've tried it both with an without the video card since I don't have a working Mac to test it in. The RAM appears to be detected, or at least it detects if there's no RAM (the sleep LED flashes if I install the RAM in the wrong sockets, or turn it on with no RAM). I assume it should chime and boot without a video card?

    I've tried it with one CPU in socket A, or socket B, and I've swapped the two between sockets. If I only have CPU A installed, then CPUA FAIL lights up, in all other combinations, CPUB FAIL lights up.

    I have thoroughly checked the board over for obvious damage. I have also checked the power supply voltages. I had some free time over the holiday, so as a last resort, I un-soldered the firmware chip, and reprogrammed it with the file contained on the emergency firmware recovery CD using an EPROM programmer. I did try the normal emergency recovery procedure first, but the sleep LCD flashed quickly, and the DVD drive didn't open. There was no change, so I flashed the original firmware back since the recovery image is missing the serial number, and possible other things. If anyone want a copy of the extracted firmware for some reason, send me an email.

    I'm en electrical engineer, so I could do component level repair if I knew where to start. It would be nice if I had some idea of how it failed. Does this logic board have any known weak points such as soldering problems?

    Apart from some cosmetic damage, it looks like new, so it didn't die of old age. The fans and heat sinks are absolutely spotless. Before I call it a dead logic board, is there anything I'm missing?
  2. 666sheep macrumors 68040


    Dec 7, 2009
    I assume you did SMC and SYS_RST?
    MP should run with one CPU placed in A socket, this is confirmed many times, so this CPU A error does not sound too good...

    Are CPUs SLR9X (B2 stepping)? Original should be SLR9X IIRC. There are three more stepping versions See 5130 specs.

    If you have ability to flash EFI chip in standalone programmer, maybe you can try updated BootROM:
  3. bearcatrp macrumors 68000

    Sep 24, 2008
    Boon Docks USA
    Any way you could check the cpu's on another mobo to insure there not dead? Xenon usually don't die. I have 2 of those chips collecting dust now as I upgraded my old map pro one years ago (sold now) but it does sound like a dead mobo. You probably want a original Mac gpu as video cards in the pro's are know to implicate a bad mobo. Strange it's showing only CPU B is bad when both chips are installed but A is showing dead when using either one in socket A only. My suggestion would be have nothing attached, use only a good Mac gpu and minimal memory, then swap CPUs around again and see what happens. Good luck.
  4. andy2000 thread starter macrumors newbie

    Dec 29, 2010
    Thanks for the suggestions. I managed to extract the firmware image from the update, but there's no change. I think it's safe to say it's not a firmware problem. I wanted to rule it out because I've run into it before with dead PC motherboards (even with ones that are supposed to have a backup BIOS).

    I find it very hard to believe that both CPUs have failed, and from what I've read, it should work with one CPU (although I've read conflicting reports on which socket to use). The CPUs are both SLR9X, and they don't look like they were ever removed. I have a few single Xeons sitting around that I've tried (including a real 5140, and a couple of engineering samples).

    Could bad, or incompatible RAM cause these symptoms?

    Should it boot with no video card?
  5. FireArse macrumors 6502a

    Oct 29, 2004

    With component isolation, the last thing you want to do is put a 'flashed' GPU which you're unable to determine actually works.

    Hunt a known (in a Mac Pro 1,1) working NVidia 7300GT and try use all known good peripherals, else you'll forever be questioning whether its the CPU, MLB or the dodgy parts you've used.

    Desktop Macs won't chime without a GPU.

    Good luck
  6. 666sheep, Dec 30, 2010
    Last edited: Dec 30, 2010

    666sheep macrumors 68040


    Dec 7, 2009
    Wrong. OFC they do chime. PCIe ones. G5 Dual Core and MP 3.1 I've tested personally (not once). I will try with my current MP 1.1 and will update this post.

    Edit: Mine 2006 chimes and boots without GFX installed. It's accessible via SSH or VNC when it runs headless.

    Yes, it should. Try this.
  7. andy2000 thread starter macrumors newbie

    Dec 29, 2010
    That's good to know. Thanks for checking. For what it's worth, I've been doing all my testing without the video card, and it has never chimed, or recognized the keyboard.
  8. lewdvig macrumors 65816


    Jan 1, 2002
    South Pole
    +1 as this is very good advice. It's good to keep one of these handy even after you move on top something faster.

    Kind of like keeping an old Rage 128 card around in the PowerMac days when we were flashing generic RADEON 9700 cards to work on our Macs. Things never change. :)
  9. Quaam macrumors newbie

    Feb 11, 2012
    los angeles
    I have noticed on my mac pro 1,1 that wether it chimes or not depends on if the volume is up or if its muted in os x. I used to have my mac muted and would get no chime during startup, until I increased volume.

    This included the normal chime and the error chimes.

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