Mac Pro early 2009 gpu ok flashing intermittent boot issue

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Level 1

7 points

Mac Pro early 2009 gpu ok flashing intermittent boot issue

Hi,

Was wondering if anybody has any advice or could help me with an issue I am having on my Mac Pro Early 2009 model.

The issue that I am having is an intermittent boot issue. This issue just began all of a sudden one day I tried to power on the desktop but it wouldn't start. After many attempts it powers on but after shutting down, it won't restart. After many attempts again it boots, but only maybe after about 20-30 if I had to guess.

Fans and lights go on but no chime.

Pushing of the diagnostic button on the motherboard reveals a "gpu ok flashing".

Suspecting it was indeed the gpu, I replaced it with an Nvidia GeForce 9800GT after installing the appropriate drivers. After multiple attempts it worked and booted ok, but again after shutting down it had the same issue, it wouldn't restart.

Things I have attempted but still the same issue:

Tried putting the video card in different pci ports.

Tried booting with both cards.

PRAM reset.

SMC reset.

Battery board replacement.

Disconnecting DVD drive.

Reseating RAM (checked board for bad RAM lights).

Powering on with no drive.

Swapping DVI cables.

Trying to update EFI (however this was not possible as shutting down, would result in computer not starting.

Checking heating for wobbly issue.

The start issue persists but when the computer turns on it works perfectly.

Anybody have any suggestions, would appreciate if anybody could reply with any help.

Thanks!

Mac Pro, iOS 10.3.3

Posted on Jul 24, 2018 12:20 PM

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Answer 1

Sep 11, 2018 8:54 AM in response to degru

Those marks mean nothing. They are likely inspectors' marks from when the board was built.

The only indicator that is meaningful is if their tops are dished up, indicating they got so hot the electrolyte inside boiled.

There is not that much logic on the mainboard in a 2009 thru 2012 model. Mainboard failure is not common.

You may want to identify a source for a replacement power supply. If your debugging does not point elsewhere, that may be needed soon.

you should probably check for wiggly northbridge chip, but your symptoms do not match the most common ones. Dis-assembly is not required for this check.

http://www.xlr8yourmac.com/archives/jul14/071114.html

.

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Answer 2

Sep 18, 2018 5:47 PM in response to degru

Any chance it could b some firmware corruption?

No.

The firmware self test is one of the earliest ones. If it fails, you get a specific pattern of blinking in the Power-on light.

And in case your next thought is Bad RAM, that is also impossible on these models. They have Error Correcting Code RAM.

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Answer 3

Jul 31, 2018 11:22 AM in response to degru

Is the power-on/sleep light blinking a code?

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Answer 4

degru Author

Level 1

7 points

Jul 31, 2018 9:05 AM in response to degru

Thought I might try leaving it on sleep instead of shutting down, that way could just leave it in this state and wake it only when I needed to use it, however it looks like when it goes to sleep, it doesn't wake properly. All fans spin and power comes back but nothing else. Anybody? Any ideas?

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Answer 5

degru Author

Level 1

7 points

Jul 31, 2018 9:35 AM in response to degru

Sometimes the GPU OK error light does not flash, however is will still not POST. The f not power button stays lit, it does not flash. I have included a pic of all lights on, don't think I can upload video of error, however it is just GPU OK light flashing. It looks like the error however does not affect the ability for the desktop to start.

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Answer 6

degru Author

Level 1

7 points

Sep 11, 2018 8:28 AM in response to degru

Noticed there were two capacitors on the logic board near the pci express card slots that have a marker line drawn on them. Would this indicate that at some point the capacitors were changed or is this done from new? I bought this mac pro used. I will post a pic as soon as I get a chance.

thanks

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Answer 7

degru Author

Level 1

7 points

Sep 18, 2018 3:45 PM in response to Grant Bennet-Alder

Hi Grant, thanks for the response. I took a look at the capacitors and they don't look swollen. I did manage to start the computer today again after many many attempts, but again after it is shut down it won't restart. I also took a look at the link and the northbridge but seems ok.

I was looking at the cost of the psu and they are quite costly and most of the time refurbished with not much of a warranty, wish I had another one to troubleshoot with and find out for sure before looking at a replacement.

Any chance it could b some firmware corruption? Probably not though as I reinstalled 10.6.8 on another drive and doesn't have any effect.

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Answer 8

degru Author

Level 1

7 points

Sep 18, 2018 6:00 PM in response to Grant Bennet-Alder

I had that thought a while ago, tried swapping them out and installing them one at a time, didn't realize they were error correcting ram, now I know thanks to you that that process was a waste of time lol.

Well I guess the next thing would be to try to somehow get a psu to test it maybe I will have to roll the dice and buy one although I will have to decide if it is worth it. If I end up trying another psu and it doesn't work, any other things it could be? I originally thought that it was the video card because the last light was flashing on the indicator lights but I have ruled that out with another gpu.

Thanks

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