Page 2 of 3 FirstFirst 1 2 3 LastLast
Results 21 to 40 of 48

Thread: Mac Pro not booting

  1. #21
    Join Date
    Feb 2012
    Posts
    265

    Default

    8800GT arrived, installed and all is well.
    It was an interesting exercise though, as I'd had startup freezes before with defective cards, but I'd never bothered to check whether it was actually booting through in the background behind the apparent freeze.
    This may well turn out to be a valid test for whether a freeze is due to video or drive/OS issues. If it shows up on the network after a 'freeze' then you know it's going to be a video issue as the OS has loaded. There's no logical reason why a video card should prevent startup as any mac is capable of booting without a video card installed.
    I think I'll go and test that theory on an iMac that's got a dead video chip on the logic board...

  2. #22
    Join Date
    Mar 2001
    Location
    Virginia... where one Democrat CAN make a difference
    Posts
    2,929

    Default

    Quote Originally Posted by unclemac View Post
    I think you will find a surprising lack of BS around here.
    Wow I've heard some whoppers before but..... dang!



    Ought to be ashamed, Unc.
    Damien,

  3. #23
    Join Date
    Feb 2001
    Location
    on the landline, Mr. Smith
    Posts
    7,784

    Default

    Yeah......that was BS wasn't it?

    What I should have said: .....lack of BS about Macs and Tech. Everything else? Watch your butt.


    Video interrupting video:

    Way over my head, but sure seems there has always been a direct and sensitive Mac OS booting and video card relationship at the firmware level. Was there in the Open Firmware days, and seems to continue with EFI.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  4. #24
    Join Date
    Jan 2002
    Location
    NW Montana
    Posts
    8,197

    Default

    Yup,

  5. #25
    Join Date
    Feb 2012
    Posts
    265

    Default

    Had two 24" white iMacs in this week, both with bad video boards. One was a 7300GT, the other, unusually, a 7600GT.
    Different symptoms, but both needing replacing.
    One booted to the desktop and was okay to a point, but then the lines would start to appear and windows fragmented when moved. The other was similar to the Mac Pro, it did fragment instantly on boot up though leaving no doubt where the problem was. Booting off a drive set to auto login and share meant that I could see where it was in the boot process in spite of the screen freezing the moment the grey Apple symbol went from the screen. It was going all the way through so very easy to be sure that the 7600GT was the only problem to deal with.
    When I get them out I'll have a look at the capacitors and see if they're showing signs of decay. I'm no expert with a soldering iron, but I have a friend who builds holographic lasers for a living so he'll have a poke around and see if the problem is one that can be repaired.

  6. #26
    Join Date
    Mar 2001
    Location
    Virginia... where one Democrat CAN make a difference
    Posts
    2,929

    Default

    Don't have a capacitor replaced .... have ALL the caps replaced. At least all of the same size and specs as the one that went bad. That was a HUGE quality spill at the plant that made those caps and pretty much every big name electronics maker had big issues because of it. My mom had three new motherboards in hers, courtesy of Apple and when I removed the back it was never just one cap, many would be swelled and more than one would be leaking
    Damien,

  7. #27
    Join Date
    Feb 2012
    Posts
    265

    Default

    Thanks Damien, that was pretty much what Tris was saying, and for the cost involved it's worth doing them all anyway.
    If it is just the caps causing the problem then that will be $170 saved on each one... just about to start taking them apart for a look-see.

  8. #28
    Join Date
    Jun 2012
    Posts
    4

    Default Early Mac Pro not booting HELP!!!!!

    Hi all,
    I have an early mac pro which I have diagnosed to the best of my abilities by following the advice in some of these threads.

    I have narrowed down to this:
    with all devices removed ie graphics card, HD and RAM the following is observed on the diagnostic LEDs.

    No diagnostic leds are lit. Pressing the diagnostic button causes ONLY the trickle power LED to light and nothing else. Fans are going non stop so indicates PSU is ok. I have read elsewhere that capacitors on MB where power enters can blow and need replacing. How would I check for this? And exactly which capacitors do I need to check?
    thanks in advance for any help,
    greg

  9. #29
    Join Date
    Feb 2012
    Posts
    265

    Default

    Ah, this has just brought the thread live again.
    I had the cards replaced as there were no capacitors that could be replaced even if I could have identified them.

    GG23... if you are going to get involved in component level repairs you need an awful lot of information and a hell of a lot of luck.
    Most of the components on the logic board are unidentifiable as they are not generic components so even if you were able to diagnose a problem the chances of you fixing it are virtually nil.
    Once a logic board has been determined to be the problem 999/1000 you will either get a new logic board, if the value of the Mac is high enough to warrant the expense, or you will write it off and sell it for parts.
    As it's a Mac Pro, it will still have a relatively high value, but then so will a logic board.
    Current price of a 2008 logic board in the UK is 295 so it would still be worth doing.

  10. #30
    Join Date
    Jun 2012
    Posts
    4

    Default

    hi macloon,
    Thank you for the reply. Do the symptoms indicate that it definitely IS the MB. Is there any way of confirming this other than swapping in a whole new MB?

    Thanks
    greg

  11. #31
    Join Date
    Feb 2001
    Location
    on the landline, Mr. Smith
    Posts
    7,784

    Default

    Exactly which model is it?

    I expect the loon is right, but we can dig a little to see if there are any other options.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  12. #32
    Join Date
    Jun 2012
    Posts
    4

    Default

    the machine has numbers A1186 and MA356LL/A so Im asuming its a 2008 model 2.66Ghz dual Core

  13. #33
    Join Date
    Feb 2012
    Posts
    265

    Default

    Pressing the diagnostic button causes ONLY the trickle power LED to light and nothing else. Fans are going non stop so indicates PSU is ok.
    No, that doesn't indicate that the PSU is okay, it only shows that there is trickle power there. That doesn't mean that it is going to power the Mac.
    The other LEDs, 3 to 6 are down to the processors and would normally be off anyway.
    LED 7 should be lit when you've got the graphics card in. If it isn't lit then it's not communicating with the logic board. 8 tells you that the power is good so if that isn't lit, then the PSU is most likely to be the problem.
    9 is indicating that EFI is loaded, but that won't happen unless the machine is powered up.
    My bet it that your problem is in the PSU and not the logic board.

  14. #34
    Join Date
    Feb 2012
    Posts
    265

    Default

    Sorry, just checked the LED lists and it may be that you only have 8 LEDs on your board, in which case you're getting #1 light up. If that's the case then nos 2-5 relate to the processor and should be off. The comments I made above related to a newer model than yours that also has a sleep LED that is #1 out of 9.

  15. #35
    Join Date
    Jun 2012
    Posts
    4

    Default

    hi NacLoon,
    You were right the first time. There are 9 leds, number one being an empty slot labelled "SLEEP"? Ive attached a pic to confirm

    So you are saying that it still could be the PSU even though the fans going?

    Theres hope!!! I guess he next thing would be to test the PSU. If I disconnect it from the MB could I check the voltages at the plugs? WOuld this be enough or do they need to be tested under load?

    Thanks for your help
    greg

  16. #36
    Join Date
    Feb 2012
    Posts
    265

    Default

    Power supplies do need to be tested under loads. About the only thing you can test a power supply without a load for is to see whether there is power coming through or not. The fans don't draw much power so that's not much of a test of a PSU.
    The best solution is to get one to swap out, if you can get one you can try without buying it. The other option is to send it off to get it checked and repaired. I can give you a name and number if you want to go that route. Normal cost of a repair is 55 plus postage. I've done it many times when I can't get a replacement at a reasonable price.
    At least if you get it tested it's in the right place for a repair and it will only cost you more than postage if it's in need... better than getting a new PSU and finding it really is something else.

  17. #37
    Join Date
    Feb 2001
    Location
    on the landline, Mr. Smith
    Posts
    7,784

    Default

    Progress.......
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  18. #38
    Join Date
    Nov 2013
    Posts
    7

    Default Thanks

    Old threads are sometime the best...

    Just registered - as the earlier 'you can boot a MP without a video card' tip has just helped me isolate the problem with a faulty MP over the weekend and wanted to say thanks

    Its a 2008 3.1 with the 2600 card and boot fails every time with the blue screen that follows the grey. I'd tried lots of the steps mentioned earlier in the thread - memory, disk swaps then found this post. I was suspecting the power supply tbh.

    But as soon as I made the boot disc autologin and accept remote management, i could login and screen share without the videocard installed - result.

    I've since temporarily installed a low end 5450 and booted linux, just to isolate any potential power issues with the PCIE slot. It's definitely the 2600.

    So i've just ordered a GTX 650 Ti, as was planning on upgrading to Mavericks. Am now thinking it might not be straightforward/possible and wanted to see what other think?

    It's currently on 10.6.8 and so valid for Mavericks, but without a supported video card - is it even possible to do the upgrade?

    Will have a read round the rest of the site now that I'm in a more positive frame of mind

  19. #39
    Join Date
    Feb 2012
    Posts
    265

    Default

    If it will boot 10.6.8 it should boot 10.9. I've not come across anything yet that fails because of a driver issue in Mavericks... although I am finding more software that doesn't like it too much!
    The opposite of what you automatically assume to be the truth is the answer you're looking for!

  20. #40
    Join Date
    Nov 2013
    Posts
    7

    Default

    Yep I think the 2008 is ok with Mavericks. Was more thinking about the lack of the working video card, meaning I cant see the last parts of the upgrade process. If i'm screen sharing from my macbook then I can run the Mavericks app on the MP but when it reboots will i still be able to access it?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •