Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Sample

macrumors member
Original poster
Dec 7, 2015
72
18
For unknown reasons, randomly all front and back USB ports stop working and a horizontal zig-zag line appears over the bluetooth symbol on the top finder bar. No input is possible and the only way out is to manually shut down the Mac.

1) Usually if I wait a while it goes back to normal after restarting, could it be an overheat issue?
With ambient at 33° the Northbridge Diode can reach up to 77°…

2) Or is my Mac’s main board about to give up?

Please give me some advice, really have no clue on this one..🤔
Thanks for your help guys
S
 
Your Northbridge is pretty hot.
This may help https://forums.macrumors.com/thread...mp-reduction-in-dual-cpu-cmp-4-1-5-1.2179729/

PS : There is NO "PRAM" reset for cMPs However there is the "NVRAM Reset as shown below,

IMPORTANT :

1. Shut the cMP down first.

2. Remove the power cord for 5 minutes.

3. NOTE : If you have any USB 3.0 / 3,1 cards in PCIe slots try removing them prior to doing the NVRAM Reset

=======================================

I cannot stress enough that the keys must be HELD DOWN until you hear THREE TIMES CONTINUALLY ( four times is OK too ).

NVRAM_PRAM_ResetMac.jpg
 
Just a guess: how old is the battery?

Another setup you could try is with a wired keyboard and mouse , bluetooth switched off and no PCIe cards , only the GPU, no peripherals connected.
 
Last edited:
Your Northbridge is pretty hot.
This may help https://forums.macrumors.com/thread...mp-reduction-in-dual-cpu-cmp-4-1-5-1.2179729/

PS : There is NO "PRAM" reset for cMPs However there is the "NVRAM Reset as shown below,

IMPORTANT :

1. Shut the cMP down first.

2. Remove the power cord for 5 minutes.

3. NOTE : If you have any USB 3.0 / 3,1 cards in PCIe slots try removing them prior to doing the NVRAM Reset

=======================================

I cannot stress enough that the keys must be HELD DOWN until you hear THREE TIMES CONTINUALLY ( four times is OK too ).

View attachment 1806619
Thanks MIKX for your 2 suggestions:

1) I have read the post, at 30° ambient I had 74° on the Northbridge Diode and had been told on this forum that it was normal, now at 33° ambient I have 77°, do you think it’s mandatory for me to install an additional fan for it?
6 months ago I had already repasted the Northbridge and replaced the old plastic rivets with the metal nut and bolt method...

2) I have redone the PRAM reset following your guidelines, the only PCI card I have is a OWC Accelsior for an SSD.
I can’t immediately say if this fixes it because of course now USB is working, otherwise I couldn’t have done the PRAM reset:) btw I had already done the reset (without unplugging the PSU though) and the issue popped up again and again…


Just a guess: how old is the battery?

Another setup you could try is with a wired keyboard and mouse , bluetooth switched off and no PCIe cards , only the GPU, no peripherals connected.
Thanks KeesMacPro:

1) Battery is new, I put a new one 6 months ago (when I repasted the Northbridge and CPUs)

2) I only use a wired USB hub to which I connect a wireless key board and mouse, but at all times I always have also a spare wired keyboard that's USB connected at all times in order to perform boot operations, bluetooth not working is not a big issue for me since I do not use it.

Guys, do you think this is a symptom of a failing hardware? Maybe the mother board? This is the ideal time for me to takle this kind of issue and eventually make hardware replacements or upgrades before the busy working season starts, please give me your opinion on this, if I need to bite the bullet and purchase a new motherboard or anything else you suggest then I'm ready to do it now, I dread the idea of a hardware failure when in the midst of the working season....
 
  • Like
Reactions: KeesMacPro
Thanks MIKX for your 2 suggestions:

1) I have read the post, at 30° ambient I had 74° on the Northbridge Diode and had been told on this forum that it was normal, now at 33° ambient I have 77°, do you think it’s mandatory for me to install an additional fan for it?
6 months ago I had already repasted the Northbridge and replaced the old plastic rivets with the metal nut and bolt method...

2) I have redone the PRAM reset following your guidelines, the only PCI card I have is a OWC Accelsior for an SSD.
I can’t immediately say if this fixes it because of course now USB is working, otherwise I couldn’t have done the PRAM reset:) btw I had already done the reset (without unplugging the PSU though) and the issue popped up again and again…



Thanks KeesMacPro:

1) Battery is new, I put a new one 6 months ago (when I repasted the Northbridge and CPUs)

2) I only use a wired USB hub to which I connect a wireless key board and mouse, but at all times I always have also a spare wired keyboard that's USB connected at all times in order to perform boot operations, bluetooth not working is not a big issue for me since I do not use it.

Guys, do you think this is a symptom of a failing hardware? Maybe the mother board? This is the ideal time for me to takle this kind of issue and eventually make hardware replacements or upgrades before the busy working season starts, please give me your opinion on this, if I need to bite the bullet and purchase a new motherboard or anything else you suggest then I'm ready to do it now, I dread the idea of a hardware failure when in the midst of the working season....
I would message @tsialex and ask if this might be a symptom of corruption/issues with your bootrom. See MP5,1: BootROM thread | 144.0.0.0.0
 
please give me your opinion on this,
IMO the Temp NorthBridge is a bit high, but I doubt this would cause these symptoms.
Nevertheless , in a DUAL MP 4,1/5,1 the NB tends to run hot with default fan settings.
You could set in MacsFanControl:
- Intake sensor NB diode min 55, max 75 Degrees
- CPU A sensor NB diode min 55, max 75 Degrees

Another suspect could be the USB hub you mentioned.
You could test without the hub and see what happens.

Before testing this I wouldnt suspect worst case scenario (faulty backplane).
 
IMO the Temp NorthBridge is a bit high, but I doubt this would cause these symptoms.
Nevertheless , in a DUAL MP 4,1/5,1 the NB tends to run hot with default fan settings.
You could set in MacsFanControl:
- Intake sensor NB diode min 55, max 75 Degrees
- CPU A sensor NB diode min 55, max 75 Degrees

Another suspect could be the USB hub you mentioned.
You could test without the hub and see what happens.

Before testing this I wouldnt suspect worst case scenario (faulty backplane).
Thanks again KeesMacPro, as a matter of fact I always have a wired USB keyboard connected at all times and when the USB fails that fails too so I gather the hub is not the culprit, looks like the problem is related to all the USB ports simultaneously.
 
Thanks again KeesMacPro, as a matter of fact I always have a wired USB keyboard connected at all times and when the USB fails that fails too so I gather the hub is not the culprit, looks like the problem is related to all the USB ports simultaneously.
You're welcome Sample!

Personally, i'm not sure if your deduction is 100% waterproof....
I suppose a malfunctioning hub could cause all kind of side effects , including all USB ports stop working.
It's a matter of 1 minute to disconnect the hub and see what happens...
Anyway, that's my point of view;)
 
You're welcome Sample!

Personally, i'm not sure if your deduction is 100% waterproof....
I suppose a malfunctioning hub could cause all kind of side effects , including all USB ports stop working.
It's a matter of 1 minute to disconnect the hub and see what happens...
Anyway, that's my point of view;)
You're perfectly right, as soon as the issue pop up it'll be the first thing I try:)
 
  • Like
Reactions: KeesMacPro
I don't think that this is a BootROM or NVRAM related issue. Usually when it's BootROM/NVRAM related you have the problem right from the moment macOS is loaded, or when you connect a USB device, and not an intermittent failure.

This seems more more a hardware/overload issue.
 
I'd start removing any USB hubs and installing a pair of known working with other Mac/brand new keyboard/mouse. If you still have the problem, replace the backplane for another one with the same SMC version. An early-2009 Mac Pro, needs an early-2009 backplane.
 
  • Like
Reactions: Sample
I'd start removing any USB hubs and installing a pair of known working with other Mac/brand new keyboard/mouse. If you still have the problem, replace the backplane for another one with the same SMC version. An early-2009 Mac Pro, needs an early-2009 backplane.
Hi guys, tsialex was right, I tried disconnecting the recently purchased CyberPower CP1500PFCLCD's USB cable from my Mac Pro and the issue has not reappeared once in the last 2 months, looks like the UPS was too demanding for the USB ports.
Thanks again tsialex and all you guys for your kind support! :)
S
 
  • Like
Reactions: tsialex
The USB from the UPS is purely for data, so it can talk to your mac when it's on battery power.

The UPS powers the mac (through the power cable), not the other way around.
 
The USB from the UPS is purely for data, so it can talk to your mac when it's on battery power.

The UPS powers the mac (through the power cable), not the other way around.
Thanks MarkC426:), yes of course I know the UPS doesn't draw power from the USB but uses it only for data, but I guess something about the the data transfer to and from the UPS must have been "overloading" in some way the USB since the issue started right after I started using the UPS and stopped right after I unplugged the USB cable 2 months ago...
Unless it's been an incredible coincidence and the issue starts again in future that is :oops:
 
Sounds like a problem with your USB ports.
I have had a Cyberpower UPS attached for years.
 
:eek: It didn't occur to me to read it like that...
I wonder if there's a way to check the health status of the USB ports? WIth normal geat like external drives, keyboards etc they seem to work fine...
 
Don't mean to state the obvious, but you where using the usb on the rear (not the charging points on the front).
 
Don't mean to state the obvious, but you where using the usb on the rear (not the charging points on the front).
nothing is ever too obvious in these cases thanks:) btw yes, I only used the 3 rear ones....
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.