Mac Pro 3.1 / rebooting / GPU

Discussion in 'Mac Pro' started by edgley, May 3, 2014.

  1. edgley macrumors newbie

    Jul 28, 2008
    Seems to be that time of year for problems for us 3.1ers.
    After 7 years of no problems I cant complain, never had a PC do more than a couple.

    Anyways, thought it was the GPU, so put in another 8 series, but still reboots. Have ran memtest for the day, no problems.

    I know the RAID is good as I can boot it up via FireWire on my MacBook (so cool, had no idea). Guess I am of to find another GPU to try, but any other ideas please?

    (just noticed my join date, same time as this giant metal beast came into my home)
  2. OS6-OSX macrumors 6502a


    Jun 13, 2004
    Is your 3,1 clean enough to eat off of? :p
    Check your PSU for signs of a dust storm!

    Attached Files:

  3. edgley thread starter macrumors newbie

    Jul 28, 2008
    She used to be, but of late....

    Will go find the air cans and go make some mess :D
  4. NOTNlCE macrumors 6502a


    Oct 11, 2013
    DMV Area
    Heat and dust cause tons of problems. Blow that guy out and give it a shot. I once "fixed" my friend's Quad G5 by taking an air compressor to the thing. It wouldn't even power on, and then POOF. Totally fine.
  5. edgley thread starter macrumors newbie

    Jul 28, 2008
    Did give it a clean, must admit that it really wasn't that bad at all.
    Even found another video card, almost the same type exactly.

    Unfortunately, still doing the rebooting thing. I might be able to borrow another card to try, but any other tips please? I cannot get used to using this Mac Mini which is, well, slow :p
  6. NOTNlCE macrumors 6502a


    Oct 11, 2013
    DMV Area
    Check your Logs, see what is causing the reboot. Also, try booting with less RAM, I would try just two sticks at a time, if your system will boot with two sticks. Frequently, issues are caused my dead RAM.
  7. edgley thread starter macrumors newbie

    Jul 28, 2008
    Will do, so even though its rebooting at the start up grey screen there will be a log somewhere?

    I did run memtest on it for 48hr and it showed nothing wrong. Am hoping you/someone is going to tell me that that don't prove nothing (as this hasn't crossed my mind, he thinks as he goes to get his old Pro and have another go).
  8. fuchsdh macrumors 65816


    Jun 19, 2014
    I've on occasion had similar issues with my Pros at work--they'd randomly shut down. I believe it had something to do with abnormal temp readings, rather than a GPU or PSU issue--cleaning the computer out, reseating the RAM, letting it cool for a few minutes, and then making sure it had enough airflow out the back did the trick.
  9. soulbot macrumors member


    Feb 8, 2008
    I really hope you find some help here. I have the same machine, same problem. I'm about an inch from putting it out to pasture… whatever that means? Sell it for parts? I don't know what to do if it's completely dead. Anyway, it's so frustrating because I feel like the solution should be more clear. But it's not. And I've gotten a LOT of feedback.

    I've been battling this for a year now. Last summer, my 3,1 had been acting funny: random reboots, random shut downs (no reboot), fans REVVING, non-booting. SMC resets wouldn't square it up, there in the "end". So, my clues were pointing to PSU. I replaced it and it ran like a dream, again. But only until recently. Now it's got all those same issues. Again. I've been pulling my hair out. Actually, I'm past that now, I'm more focused on an 'exit strategy'. But I got in touch with this guy on ebay that was selling power supplies. I asked him if a PSU could fail within a year, like this one may have. He said, "…I've handled hundreds of Mac Pro computers and your situation seems very odd. In my experience, the power supply is usually one of the last things to malfunction or go bad. That said, it's not out of the question…" Basically he dissuaded me from buying yet another PSU. But I still didn't have any answers.

    I started this thread on the Apple forums. One fellow there offered some things that seemed to be common fixes with other posters with similar symptoms:

    I don't know what your solution will end up being, but I can give you a few ideas of what other Users have shared:

    • Dust Bunnies

    • disconnected cable to the temp sensor -- this will be detected by Apple hardware test

    • heatsink loose or off the "Northbridge" system controller, due to broken plastic screws

    • sloppy initial application of heat transfer compound at the CPUs -- (not likely, or your CPU temps would go nuts).

    So, I was able to rule out: #2) Apple Harware test always says, "no problem found". I ruled out #3, Northbridge issues. It was good to go. Ruled out #4 because my CPU temps were just fine / normal. So that only left me with #1: Dust Bunnies. I was hopeful as it's great when the simplest / cheapest solution is the one that works. Canned air weren't enough for me. I bought a HIGH-strength blower and cleaned it out. Sure a few bunnies blew free, but nothing too astonishing. Anyway, the machine did indeed work again. For a while. That very next power up was great! I let it run all night. It ran for 12 hours straight — no issues at all.

    But that was a few months ago. Slowly my issues have all crept back. I reseat cards, SMC resets. memtest says everything is a-okay. I'll swap RAM around. I'm at my wits end. (I bought a MacBook Pro last April and that plus a big bad NAS are likely going to be my way forward from here on.) But I'd love to figure out what's up with the Mac Pro. Now it basically will not stay on. It may—but for no longer than 15 minutes. Sometimes it's very very slow to boot. Sometimes it will "double-boot" and get going. Sometimes it will turn on, but no boot chime. It will usually get going at some point, but in the end it's pretty much irrelevant, because minutes later it's going to power back down.

    I don't know. I live on Maui. It's wet here. I run a dehumidifier quite often, but I've noticed a little corrosion on some logic board components… so maybe that's my issue. I'd love to KNOW something more definitive, but I don't think it'll come to that.

    Finally, here's one final thread I started. There's a link in it that will redirect back to a MacRumors thread because the OP there had seen this red light on the logic board that was suspicious. He never came to conclusion about what that light meant. I haven't either, as the ebay guy that helped me out, said he too had no idea what that light signifies. (It's not mentioned in the service guide. It's not really mentioned online that I could find.) In the MacRumors thread there, the dude finally concluded "I believe that led means the MP electrical management is not normal". But that's about it… Nothing completely concrete.

    Good luck. I hope you can get it running again consistently.
  10. edgley thread starter macrumors newbie

    Jul 28, 2008
    Gosh, thank you so much for taking the time to write that.

    I can offer some good news, the amount one can sell dead Apple gear is more than one can sell working PC gear :p

    My old MBP sold dead for £500, so at least some money could be got back. What you have done is saved me a lot of time. If the memory doesn't seem to be the cause I will call it a day and sell it. If I fashion in time/effort/frustration saved + cash for dead then I must be able to get something.

    I was thinking of going the route you did, get a new MBP retina and some fat storage / just that new Pro....
  11. edgley thread starter macrumors newbie

    Jul 28, 2008
    Hmm, just thought to try something.
    It does boot fine, headless.

    Might that suggest the PSU is flaky?

  12. AppleNewton macrumors 68000


    Apr 3, 2007
    1 Finite Place
    could be a power trickle issue, any diagnostic LEDs popping up. they are located in the memory bay area.
  13. soulbot macrumors member


    Feb 8, 2008
    It's difficult to say. Correlation doesn't imply causation.

    As was suggested you could play around with the diagnostic LEDs in the RAM bay to see what they suggest.
  14. 666sheep macrumors 68040


    Dec 7, 2009
    If you have described problems, MP runs headless without a problem and both GPUs you tried are 8800GT, then source of the issue is certainly 8800. Symptoms clearly point at this.

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