Mac Pro 3,1 randomly shutting down, PSU?

weezerr

macrumors regular
Original poster
Nov 7, 2006
189
91
My beloved tank 2008 octacore has been randomly shutting down on me. It seems to be worse when I try to play a video or gently stress the system. No KP, just instantly goes black and dead.

I blew out the system with compressed air, reset all the ram. Ram sticks all come up as OK in system info.

It seems like this could be a failing PSU which seems to be a problem with the 2008? Does that seem right?

Is this the correct item to buy? The part number is different than what I have found for my machine (661- 4677):

Would this work fine?

https://www.ebay.com/itm/Power-Supp...051042?hash=item3d319803a2:g:kVIAAOSw-xVZ6QNl

Thanks!
 

pl1984

Suspended
Oct 31, 2017
2,230
2,642
It could also be due to an overheating issue. Before ordering a new power supply I would recommend downloading a copy of iStat Menus and reading the temperatures. Post them to the forum where others can provide feedback as to whether they're a source of concern.
 

tsialex

macrumors 604
Jun 13, 2016
7,616
8,347
Brazil
My beloved tank 2008 octacore has been randomly shutting down on me. It seems to be worse when I try to play a video or gently stress the system. No KP, just instantly goes black and dead.

I blew out the system with compressed air, reset all the ram. Ram sticks all come up as OK in system info.

It seems like this could be a failing PSU which seems to be a problem with the 2008? Does that seem right?

Is this the correct item to buy? The part number is different than what I have found for my machine (661- 4677):

Would this work fine?

https://www.ebay.com/itm/Power-Supp...051042?hash=item3d319803a2:g:kVIAAOSw-xVZ6QNl

Thanks!
Check your board for signals of corrosion on the chips/pads of your board, I had to change two corroded logic boards boards with that shutdown problem.
 

ActionableMango

macrumors G3
Sep 21, 2010
9,512
6,772
Check your board for signals of corrosion on the chips/pads of your board, I had to change two corroded logic boards boards with that shutdown problem.
I'm curious, where was the corrosion and was there some sort of unusual factor involved or did it just happen in normal operating environment?
 

tsialex

macrumors 604
Jun 13, 2016
7,616
8,347
Brazil
I'm curious, where was the corrosion and was there some sort of unusual factor involved or did it just happen in normal operating environment?
A little bit everywhere, two Macs originally from cities that have strong sea air corrosion, don't know the correct english term for "maresia".

I still have both boards, I can take pictures of what is corroded. One you can see it clearly, the other is subtle.
 

tsialex

macrumors 604
Jun 13, 2016
7,616
8,347
Brazil
This is the less corroded one, if you just look rapidly on the board you think that is almost new. The other is a lot worse.

Look at the SMD inductor:
9FCB346F-1589-4399-AA65-E1F72859D0EE.jpeg


Processor A socket, every capacitor, south bridge heatsink:
76B38E14-0DCF-4E4B-A85F-763B64970660.jpeg
BDF947D0-D7BE-44E1-872D-6C0376633C72.jpeg


Look how the corrosion went on the pads of the TSOP FWB flash memory that stores the BootROM:
22326559-3ADF-4DBD-BA36-D8C7BE81A61A.jpeg
 
Last edited:

weezerr

macrumors regular
Original poster
Nov 7, 2006
189
91
This is the less corroded one, if you just look rapidly on the board you think that is almost new. The other is a lot worse.

Look at the SMD inductor:
View attachment 790627

Processor A socket, every capacitor, south bridge heatsink:
View attachment 790628 View attachment 790629

Look how the corrosion went on the pads of the TSOP FWB flash memory that stores the BootROM:
View attachment 790630
Thanks for the reply! the logic board looks pretty flawless to me. Im the original owner, has never been left in super humid environments.

Reasonable to throw $80 at a PSU and see if it fixes it? Is the one I linked the correct one?

I will run some temp monitors as well to check for overheating.
 

weezerr

macrumors regular
Original poster
Nov 7, 2006
189
91
It could also be due to an overheating issue. Before ordering a new power supply I would recommend downloading a copy of iStat Menus and reading the temperatures. Post them to the forum where others can provide feedback as to whether they're a source of concern.
Staying mostly between 40-46 C....
 

ActionableMango

macrumors G3
Sep 21, 2010
9,512
6,772
Shutdown reasons are logged. In some cases even sudden ones like power loss might be logged--I don't know how, maybe the log is appended on the next startup. So it doesn't hurt to check your log even though it's a sudden shutdown.

Search for "previous shutdown cause" in the log and find an entry that coincides with the time there was an unexplained shutdown. Then check the number against this list. It might provide additional clues.
 

Pressure

macrumors 601
May 30, 2006
4,059
297
Denmark
When it randomly shuts down does the PSU make a "click" noise? And do you manually have to press the power button to shut it "off" before you can turn it on again when it occurs?
 

weezerr

macrumors regular
Original poster
Nov 7, 2006
189
91
When it randomly shuts down does the PSU make a "click" noise? And do you manually have to press the power button to shut it "off" before you can turn it on again when it occurs?
No warning or click, it just abruptly shuts off.

Once I push the power button it starts back up and will last an indeterminate about of time. Sometimes a few days, sometimes it won’t make it past the fans spinning up.
 

weezerr

macrumors regular
Original poster
Nov 7, 2006
189
91
Try and blow all the dust out of the PSU but do NOT touch the capacitors.
Thats for the reply.

I just put in a "new" PSU. Thankfully I must not have broken anything as it booted up fine. It was worth the $80 shot in the dark to see if this solves my problem. Fingers crossed!

The old one certainly is dusty!
 

crjackson2134

macrumors 601
Mar 6, 2013
4,735
1,868
Charlotte, NC
Thats for the reply.

I just put in a "new" PSU. Thankfully I must not have broken anything as it booted up fine. It was worth the $80 shot in the dark to see if this solves my problem. Fingers crossed!

The old one certainly is dusty!
Don’t keep us waiting long for results, fingers crossed hoping this cured the problem.
 
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