Mac Pro mystery - blinking front led light

Discussion in 'Mac Pro' started by ositosucio, May 23, 2012.

  1. ositosucio macrumors newbie

    Sep 14, 2009
    hi guys...

    I have a mac pro early 2008 with the 2 quad core 2.8 Xeon processors.

    A few weeks ago something very strange started happening.

    I would turn my computer on and it wouldn't boot. Instead I would get a front blink light. I immediately thought it was a RAM problem so I started moving RAM around to identify a problematic chip.

    My current configuration is

    top riser
    2gb OWC-dimm4
    2gb OWC-dimm3
    2gb OWC-dimm2
    2gb OWC-dimm1

    bottom riser:
    2gb OWC-dimm4
    2gb OWC-dimm3
    2gb OWC-dimm2
    2gb OWC-dimm1

    This is what I have found:
    The computer will work and booth as if nothing ever happened ONLY when

    a) bottom riser dimm 4 and 3 are unoccupied
    b) I use the 1gb chips in those two slots that came with the mac originally

    If I put any OWC ram in those slots they computer won't boot. I even bought another riser to make sure and I get the same thing.

    Right now I am running at 14gbs because of this. I am positive is not the RAM as all the chips work when placed on other locations.

    Any ideas or tests I can run?

    I am kind of disappointed as I thought I would be running at 16gbs right now.

  2. Velin macrumors 65816


    Jul 23, 2008
    Hearst Castle
    Actually, I do think it is the RAM. If you search my prior posts, I had this same exact issue. Blinking front red light, and as I recall, it was OWC RAM that went bad.

    Pulled out the OWC Ram, no problem or issue.

    I think you need to test with new RAM in the slots you think are problematic, and see if it boots.
  3. ositosucio thread starter macrumors newbie

    Sep 14, 2009
    hello there...

    I am sure it is not the ram because I did other two new chips from OWC and the problem continued. And all chips work fine if not using those 2 slots.

    A bad chip would cause a problem anywhere it is installed correct?
  4. djjclark macrumors regular

    Feb 17, 2008
    the riser has 4 little led's on it that will be red if there is a problem. I think a red light means one of three things - bad ram, bad riser, bad motherboard. You can narrow the problem down by changing ram around, changing risers around.
  5. ositosucio thread starter macrumors newbie

    Sep 14, 2009
    thanks I have already tried all my ram and another riser. The problem only happens as explained on my OP.

    And no red lights ever from any of the risers.

  6. Mactrunk macrumors regular

    May 12, 2005
    I had a similar problem recently.
    Suddenly, my 3 year old OWC ram started causing problems.
    The good news is that they offer a lifetime warrantee.
    They sent replacement sticks and 2 of those went out in a couple of days.
    They replaced those and now all is well.
    Running fine for several months.
    Hats off to OWC for honoring the warrantee.
    I think they are a great company.
  7. ositosucio thread starter macrumors newbie

    Sep 14, 2009
    I understand that but if the ram was the culprit, wouldn't i see those red lights light up plus if a ram chip is bad it wouldn't work in any slots right?

    I have tested all of them and they all work if they are not in those slots.

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