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Mac Pro 5.1 randomly resetting, red light on motherboard

S

silvertonesx24

macrumors newbie
Original poster
Dec 23, 2008
7
0
Over the past few weeks, our Mac Pro 5.1 (12 core version) has been randomly resetting, as if someone pulled out the power and then plugged it back in. There seems to no consistency in terms of what is going on at the time, other than it is at the point now where it can't even reach the Login screen before randomly resetting. Essentially the machine is useless.

The only clue is this red light shining brightly underneath the first hard drive bay.

Any ideas? I have reset the PRAM, and reset the SMC (unplugged the computer for 15 min)

ghRDrvd.jpg
 
It looks like it is both OVTMP CPU A and OVTMP CPU B

I unplugged the machine for several hours and now currently have it up and running, but who knows for how long. I did install a stat program to check temos. Are any of my results out of order?

Iqr5fXX.png
 
Looks a bit warm for idle. Pull the CPU board and blow some air through the heat sinks.
 
OK will do. The machine ended up shutting down about 10 min after taking that screenshot. Will try again tomorrow after unplugging it overnight.
 
Run stress test and keep monitor the temperature. Poor cooling may be OK on idle, especially if your OAT is low. But will rise quickly under stress.

If cooling system is the problem, you will know it in less than a minute.

Otherwise, it should not be the temperature's problem.
 
pastrychef said:
Those temps look fine. They are much lower than what I see on mine.

View attachment 623854

I like Fahrenheit. I have difficulty visualizing celsius temps.
Click to expand...
While thats nice, only the US, Guam and Belize use Fahrenheit for weather, and never when referring to computers.

Fahrenheit literally means nothing to me or likely most people reading this, otherwise I could help.
 
Lucas Godfrey said:
While thats nice, only the US, Guam and Belize use Fahrenheit for weather, and never when referring to computers.

Fahrenheit literally means nothing to me or likely most people reading this, otherwise I could help.
Click to expand...

The same goes for me, I couldn't help if it were in celsius.
[doublepost=1459340879][/doublepost]
silvertonesx24 said:
OK will do. The machine ended up shutting down about 10 min after taking that screenshot. Will try again tomorrow after unplugging it overnight.
Click to expand...

If the light is lit up at 97F and it shuts down after 10 minutes, there's something else wrong. Your CPUs are obviously not overheating.

I don't see any benefit to trying to stress the CPUs and don't see how that's going to be even possible if the thing shuts down after 10 minutes at 97F. I suspect the CPU board or main logic board.
 
Started after being off and unplugged for 16h. Managed to get a quick shot of temps before it shut off 5 min later
[doublepost=1459345921][/doublepost]
Yj4XWz4.jpg

[doublepost=1459345983][/doublepost]How could I diagnose a possible PSU issue?
 
Do you have a PC GPU? The PCIe fan and PSU fan speed is not right, nothing too wrong, but they are not at normal idle speed.

I am not sure if a problematic GPU can shutdown the Mac (especially when the GPU is not under stress).
 
h9826790 said:
Do you have a PC GPU? The PCIe fan and PSU fan speed is not right, nothing too wrong, but they are not at normal idle speed.

I am not sure if a problematic GPU can shutdown the Mac (especially when the GPU is not under stress).
Click to expand...

Yes I do. GTX960 with Nvidia Web Drivers.
 
When it turns off, can you immediately turn it back on again?

silvertonesx24 said:
How could I diagnose a possible PSU issue?
Click to expand...

The service manual has detailed diagnosis steps starting on page 37 for "Intermittent Shutdown" problems.

Symptoms:
"Computer intermittently shuts down, restarts, sleeps"

If I were you, I'd Google for the service manual, obtain a copy, and go through that procedure.

Unfortunately intermittent problems are inherently difficult to diagnose. If the system is working at the moment you perform a test, then the test will pass.
 
The only time I have ever heard of a video card causing a Mac Pro to shut down is when it is drawing too much power. Based n the screenshots provided, there doesn't seem to be much load on the video card at all.
 
silvertonesx24 said:
Over the past few weeks, our Mac Pro 5.1 (12 core version) has been randomly resetting, as if someone pulled out the power and then plugged it back in. There seems to no consistency in terms of what is going on at the time, other than it is at the point now where it can't even reach the Login screen before randomly resetting. Essentially the machine is useless.

The only clue is this red light shining brightly underneath the first hard drive bay.

Any ideas? I have reset the PRAM, and reset the SMC (unplugged the computer for 15 min)

ghRDrvd.jpg
Click to expand...

Greetings
Just a thought, but, this inconsistent and variable activity might be related to PRAM so I'd check the voltage of the PRAM battery and replace it if low. Good luck.
Patrick
 
Trail-Hawk said:
Hi all, I have the same issue exactly same red lights. Was this ever solved???
Click to expand...


is the computer running normally?

they light up briefly when the power plug is plugged in > normal

if they light up all the time it can be a problem on the CPU tray, but also on the backplane.
unplug power, take out the cpu tray and see if they still light up without them > backplane

they no longer light up > CPU tray > CPU? or northbridge?
 
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