MP 1,1-5,1 Mac Pro 5,1 powers ON for a second, but quickly shuts off.

[tripmusic]

So a while back I was having problems with my Mac Pro 5,1 (flashed), basically it went dead. I replaced the PSU, but it didn’t fix it, but then I replaced the motherboard and all has been well for a couple months.

That is until the other day, when it just shutdown whilst running and wouldn’t power on and boot again. The power light comes on for a second, but quickly shuts off. I get 5V trickle and no other diagnostic lights are on, on both the motherboard and processor board.

First I swapped CPU’s and still wouldn’t power on. So, I broke it down into minimum configuration and was able to get it to stay on with the CPU out of socket. I put a CPU back in and was able to boot up. So I cleaned the CPU and heatsink and applied new thermal paste and it was working last night and I left it plugged in overnight. Then today I try to power on and no go. Power light comes on for a second and then it shuts down. I tried minimum config with no CPU again and it won’t turn on. I left it unplugged, went to the store for an hour and when I came back it turned on in min config, but then a few minutes later no power again.

I’ve tried different AC plugs and mains outlets as well. I’ve run ASD and the only error I get is a voltage sensor in SATA bay 3 (see attachment), but I’m not sure that’s causing the problem because I’ve disconnected the SATA cable to the motherboard when in minimum config and no difference. I’ve had this error since I put this replacement motherboard in and it was working fine.

My Northbridge rivets are OK, though one did pop through a while back, but the Mac Pro was working fine even when it was loose and once I got the rivet back in place. Northbridge temps have been 60c at idle and 70c under load.

I’ve noticed the CPU over temp light flashes after a few seconds when it shuts off. It did this last night after I shut down after having it on for a few hours. I remember this light flashing on shutdown in the past when my older motherboard was on it's way out. When it’s working fine, the light does not flash upon shutdown.

So I’m stumped and I don’t really want to spend money on the wrong component. It either has to be the motherboard or processor board, as I know I have two working PSU’s. I’ve attached the ASD SATA error and videos of it’s behavior in minimum configuration.

TL;DR: Intermittent Powering ON and boot. Shuts down after Power button pressed in min configuration. See first video.

No Power ON, quickly shuts off in minimum config

Power ON OK in minimum config

ASD SATA Voltage Error

 

[tsialex]

I honestly tried to read your post, but got me a headache. Please use paragraphs and separate your ideas, no one decipher blobs of text for free.

 

[tripmusic]

I honestly tried to read your post, but got me a headache. Please use paragraphs and separate your ideas, no one decipher blobs of text for free.

Sorry about that. I will try and clean it up. If you watch the first video, that should show you what's going on without having to read anything.

 

[tsialex]

When you can't power your Mac Pro on, if you press the DIAG button, what LEDs are lit?

 

[tripmusic]

When you can't power your Mac Pro on, if you press the DIAG button, what LEDs are lit?

2nd paragraph, 5V trickle

 

[tsialex]

2nd paragraph, 5V trickle

This is very weird, even a backplane without the SPI flash/BootROM shows the LEDs below lit:

• PSU PWROK (green)
• 5V STBY (amber)

A normal working board without an Apple OEM GPU should have these LEDs lit:

• PSU PWROK (green)
• 5V STBY (amber)
• EFI DONE (green)

 

[tripmusic]

This is very weird, even a backplane without the SPI flash/BootROM shows the LEDs below lit:

• PSU PWROK (green)
• 5V STBY (amber)

A normal working board without an Apple OEM GPU should have these LEDs lit:

• PSU PWROK (green)
• 5V STBY (amber)
• EFI DONE (green)

Yes, but you'll only get those when it actually powers on? I get all of those and GPU OK (even with no GPU installed) "when" I'm able to get it to power on and stay on. I can't get those LEDs if it won't power on. When it's shutdown, 5V STBY.

 

[tsialex]

Yes, but you'll only get those when it actually powers on? I get all of those and GPU OK (even with no GPU installed) "when" I'm able to get it to power on and stay on. I can't get those LEDs if it won't power on. When it's shutdown, 5V STBY.

To get GPU_OK lit, you need an AppleOEM GPU.

With no GPU or any third party GPU (even a real Mac Edition one), the GPU_OK LED will be off.

 

[tripmusic]

To get GPU_OK lit, you need an AppleOEM GPU.

With no GPU or any third party GPU (even a real Mac Edition one), the GPU_OK LED will be off.

Look at the 2nd video I posted about half way through. That's when it stays on with no CPU in the socket. The focus is off, but you can see the two bottom green LEDs on, which are EFI DONE and GPU_OK. I know it seems odd with no GPU installed. Maybe it's just an oddity without the CPU in the socket?

 

[woefi]

With no GPU or any third party GPU (even a real Mac Edition one), the GPU_OK LED will be off.

Sorry to selflishly plug a question here, but: Whats up, if the GPU OK does _flash_?
(This only happens if I swap my known-good single tray with a dual-tray, and only if I try with two x5690)

 

[tripmusic]

I suspect that my problem is the voltage sensor that's just gotten worse and is causing the MP to shutdown/not boot. Sucks because I only picked up this board a few months ago and feel like it was just a waste of money. With all the money I've spent, motherboard/PSU, I could've just bought a whole machine. So I'm leaning towards picking up another motherboard and crossing my fingers. If I encounter any errors running ASD, I'll contact the seller right away.

 

[tsialex]

Sorry to selflishly plug a question here, but: Whats up, if the GPU OK does _flash_?
(This only happens if I swap my known-good single tray with a dual-tray, and only if I try with two x5690)

Several people reported over the years that some early-2009 dual CPU trays are problematic with X5690 and works fine with X5680. I never got one of these trays on hand to investigate why. AFAIK, no one capable of tracking this got one of these problematic trays, so it's a mystery up to now.

Flashing GPU_OK is not on Apple documentation I have, not on ASD or Apple Technician Guide, just checked.

 

[simacc]

That is until the other day, when it just shutdown whilst running and wouldn’t power on and boot again. The power light comes on for a second, but quickly shuts off. I get 5V trickle and no other diagnostic lights are on, on both the motherboard and processor board.

Did you manage to fix this? I have a similar problem...similar that it powers on for a second and then suddenly powers off...difference is mine then turns itself back on (as if I pushed the power button) and the loop continues until I plug the power out... (crossed that out as it stopped doing it after leaving it unplugged for a bit)

 

[simacc]

 

[tripmusic]

View attachment 1794744

Did you manage to fix this? I have a similar problem...similar that it powers on for a second and then suddenly powers off...difference is mine then turns itself back on (as if I pushed the power button) and the loop continues until I plug the power out... (crossed that out as it stopped doing it after leaving it unplugged for a bit)

I replaced the Backplane and I've been running ok since. The sensor error I was getting when I initially posted this, was most likely the culprit.

Have you tried breaking everything down into minimum config and test? Maybe a component needs to be reseated?

 

[simacc]

I replaced the Backplane and I've been running ok since. The sensor error I was getting when I initially posted this, was most likely the culprit.

Have you tried breaking everything down into minimum config and test? Maybe a component needs to be reseated?

Cheers!

No, I didn't really know what minimum config is until now! I just found the Apple Technician Guide, so will look into that.

Last night I did go through all the ram sticks (removed one at a time and then cycled through each individually, so it's deffo not the ram), also removed all the hard drives...and the graphics card...and tried the reset button...no change for any of that.

However, after leaving it unplugged all night, it booted up as normal today and worked for a few minutes. I didn't see it shut down (went out to make a coffee, grrh). Anyway it's back to just shutting down after a second, like the video I posted above.

 

[tripmusic]

Cheers!

No, I didn't really know what minimum config is until now! I just found the Apple Technician Guide, so will look into that.

Last night I did go through all the ram sticks (removed one at a time and then cycled through each individually, so it's deffo not the ram), also removed all the hard drives...and the graphics card...and tried the reset button...no change for any of that.

However, after leaving it unplugged all night, it booted up as normal today and worked for a few minutes. I didn't see it shut down (went out to make a coffee, grrh). Anyway it's back to just shutting down after a second, like the video I posted above.

The reset button on these machines is just for the CMOS battery, unlike the earlier one's where it resets the backplane.

So, I have the Apple Software Diagnostics (ASD) for the 5,1. If you want to give it try, I can upload it to Dropbox and you can install it on a USB stick. It's 3 or 4 GB in size. If you can boot up with it and it stays on long enough, ASD might give you an idea as to what's the possible problem. Let me know.

 

[simacc]

Hi thanks...this is also a 4,1->5,1 single W3680 3.46 GHz

...if you want to save hassle uploading you could point me to the right dmg if it's on this page: https://www.macintoshrepository.org...e-test-aht-apple-service-diagnostic-asd-disks

How would I get it on a USB stick, unetbootin or something?

 

[simacc]

Also, seems that it sometimes fully boots and works for a while, I'm guessing it's not the EFI...or could it still be that?

 

[tripmusic]

Hi thanks...this is also a 4,1->5,1 single W3680 3.46 GHz

...if you want to save hassle uploading you could point me to the right dmg if it's on this page: https://www.macintoshrepository.org...e-test-aht-apple-service-diagnostic-asd-disks

How would I get it on a USB stick, unetbootin or something?

Ok. Yes, I have the same machine as you, though you got your CPU model or speed confused? Doesn't matter.

Apple Service Diagnostics 3S149 is what you want for the Mac Pro 2010

I don't see the instructions on that site, so I'll upload them. You don't need anything fancy to get it on USB, just follow the instructions carefully. When you boot up, hold the option key. There will be 2 versions, EFI and ASD. Boot into the ASD as it's more robust. I would just check all the test boxes, BUT make sure you have the test resume once an error is detected, otherwise it won't run through all the tests. There should be a checkbox for that. That's it. You can save the test results. I would do that. Oh, your fans will be spinning insanely during the fans test, so don't worry.

 

[simacc]

OK, cool, thanks for all your help...it's back to only turning on for a second so going to leave it plugged out over night and hopefully it'll stay on long enough to do some tests tomo.

I'm doing a fair bit of reading up on all this...starting to get my head around a few things now...never fixed one of these before (well other than basic reinstall/upgrade stuff)...

 

[tripmusic]

OK, cool, thanks for all your help...it's back to only turning on for a second so going to leave it plugged out over night and hopefully it'll stay on long enough to do some tests tomo.

I'm doing a fair bit of reading up on all this...starting to get my head around a few things now...never fixed one of these before (well other than basic reinstall/upgrade stuff)...

Yeah, I was going to suggest using another Mac if you have it, to make the USB stick, or perhaps you have a friend that does? That could be annoying if it shuts down as it's writing to it.

Hopefully, ASD won't bring up any Backplane sensor fails during testing. In that case, it could end up being a PSU that's on it's way out, which is a fairly easy swap if you find one.

Ah, you know what just came to mind also? It could be the Northbridge Heatsink. Apple used plastic rivets to secure it down and they are well-known for failure. That could explain the shutting down. Do you run any temperature software like Macs Fan Control? When powered on, if the Northbridge chip is above 80C it will shut down.

I know it's a lot to digest, but symptoms like this could end up being so many different things. When mine started giving me problems, I replaced the PSU, but in the end it wasn't that. Then I bought a used Backplane, which worked for a while, but then gave me issues, hence the reason for this initial post. It must have been that faulty sensor that ASD found because I bought yet another Backplane and all has been well.

 

[simacc]

Yeah I have another Mac, all good...I actually bought this MP only a few months ago off eBay to open up old music projects that I never finished in snow leopard (I stayed on 10.6 from 09 to 2016), and run some old software and hardware kinda thing...with some other ideas of moving my current build onto it when I eventually go M1 down the road...a time-machine...sort of a back-burner project, I just got everything back working and boom, the thing stops working. Gutted.

Yeah I have had Macs Fan Control on it the whole time...never saw anything out of the ordinary there, usually hovered around late 60s early 70s, (my room is warm usually around 25c)...it shut down around 60c today. Though I did notice the thing you mentioned "I’ve noticed the CPU over temp light flashes after a few seconds when it shuts off." since I bought it...I thought that was normal; could be something there...

Lol, yeah I've digested way too much over the last two days since this happened...though I understand these yokes a lot better now...but yeah your scenario comes up a lot on other posts...given the prices of PSUs and backplanes on eBay, and all the hassle of swapping them out, I'm half-thinking of just buying another whole 4,1 off Macfinder for £300 w/ a year warranty, and I can just take out the extras I've put in...not yet though, I'll get ASD working first and see if I get any results...I'm leaning towards PSU, but from what I've read, it could still be backplane, or both, or...

 

[tripmusic]

Yeah I have another Mac, all good...I actually bought this MP only a few months ago off eBay to open up old music projects that I never finished in snow leopard (I stayed on 10.6 from 09 to 2016), and run some old software and hardware kinda thing...with some other ideas of moving my current build onto it when I eventually go M1 down the road...a time-machine...sort of a back-burner project, I just got everything back working and boom, the thing stops working. Gutted.

Yeah I have had Macs Fan Control on it the whole time...never saw anything out of the ordinary there, usually hovered around late 60s early 70s, (my room is warm usually around 25c)...it shut down around 60c today. Though I did notice the thing you mentioned "I’ve noticed the CPU over temp light flashes after a few seconds when it shuts off." since I bought it...I thought that was normal; could be something there...

Lol, yeah I've digested way too much over the last two days since this happened...though I understand these yokes a lot better now...but yeah your scenario comes up a lot on other posts...given the prices of PSUs and backplanes on eBay, and all the hassle of swapping them out, I'm half-thinking of just buying another whole 4,1 off Macfinder for £300 w/ a year warranty, and I can just take out the extras I've put in...not yet though, I'll get ASD working first and see if I get any results...I'm leaning towards PSU, but from what I've read, it could still be backplane, or both, or...

That's cool that you have another Mac to make the USB.

Yeah that flashing red light I think is normally only supposed to flash when you unplug it, or plug it in? Based on what I experienced, I'm leaning towards the backplane having an issue, but you never know.

Even though your Northbridge temps seem ok, it still wouldn't hurt to take the main CPU heatsink off and inspect the Northbridge underneath, just to be sure. If the CPU paste has never been cleaned and replaced, it'd be a good idea to do that anyways. You will need a long handle 3mm hex wrench to take it off though. This is one tool that you really need to have if you're going to be using one of these Macs.

When I first started having my issues with my MP, I wish I had done just that, bought a used 4,1 machine, instead of wasting money on parts. For what I spent in total, I could've got a whole machine. The reason I didn't is because I'm in Switzerland. There's not many for sale here and people try and sell them for too much. I guess that's based on what the Swiss Franc is worth. And buying one through eBay from the US wouldn't be much better with the shipping.

In your case, it might be a better idea to just get another machine altogether. If you do, I'd suggest keeping the old one around for parts. If it is the backplane that's faulty and nothing else, Having an extra PSU and CPU tray on hand is a good idea in case you need to troubleshoot another machine in the future.

Let me know how the testing goes. I'm curious to see what errors, if any pop up.

 

[simacc]

So I left it plugged out for a few days, given that I noticed the longer I left it out the longer it would stay on, my bet was it might stay on long enough to run ASD.

So today I ran Apple Service Diagnostics 3S149 and it passed everything! And what's even weirder is it is working fine and it hasn't shut down since. I did some basic maintenance and reset the pram 10 times in a row. And sleep and wake has magically fixed itself (it used to crash when waking from sleep). Northbridge chip is currently 63c and hasn't been above 70c so far. Curiouser and curiouser. Fingers crossed.