Red light showing from processor/memory board

eyeangle

macrumors regular
Original poster
Jan 2, 2014
151
19
Melbourne, Australia
I searched this but found different people say different things. I recently had my logic board replaced by a mac technician and now a red LED light is always on next to the processor. Even when the Mac is turned off.
IMG_0485.JPG
The memory seems to be alright showing all 24 GB in About This Mac and the mac runs properly it's just this red light wasn't on before the logic board was replaced.
 
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WildBB

macrumors member
Mar 13, 2014
38
0
Pandora
I searched this but found different people say different things. I recently had my logic board replaced by a mac technician and now a red LED light is always on next to the processor. Even when the Mac is turned off.
View attachment 465728
The memory seems to be alright showing all 24 GB in About This Mac and the mac runs properly it's just this red light wasn't on before the logic board was replaced.
In my experience on prior Macs, if the red lights on the motherboard stay on, it indicates a problem/failure/error/temp issue...etc... Not sure about the newer model, but I am guessing it follows suit.

Why don't you return it to the Mac tech who worked on it and ask him to troubleshoot. I think it is like having your engine light come on in your car... it could be quite a few different things.
 

APlus84

macrumors member
Sep 13, 2009
33
1
Hawaii
Occasional Light

I get an occasional (infrequent) blinking of this same light. Today it was when I was making an MKV with HandBrake. Handbrake does like to use the processor.

Mac seems to work fine.

Service on Molokai is not an option so any ideas would be appreciated.
 

mikeboss

macrumors 65816
Aug 13, 2009
1,295
478
switzerland
excerpt from the service manual:

Processor Diagnostic LEDs
The dual-processor board and single-processor board include a diagnostic LED for each processor. The following illustrations show the location of each LED and its associated processor. These error LEDs are normally off. A red illuminated LED indicates the associated processor may be missing or in overtemp state (PROCHOT).
 

APlus84

macrumors member
Sep 13, 2009
33
1
Hawaii
Thanks.

Hopefully, it is just a little cooling. It is dusty here as we don't run A/C at $0.46KWh. I'll check it out.
 

martyr

macrumors newbie
Jun 19, 2007
26
9
Thanks.

Hopefully, it is just a little cooling. It is dusty here as we don't run A/C at $0.46KWh. I'll check it out.

Hey There,

I'm getting the same flashing light on one of my dual CPUs. Typically only happens during a stress test like Geekbench. I'm assuming it is temperature related.

Curious if you investigated it further, etc.

Thanks!

Josh
 

tsialex

macrumors 604
Jun 13, 2016
7,836
8,473
Brazil
Hey There,

I'm getting the same flashing light on one of my dual CPUs. Typically only happens during a stress test like Geekbench. I'm assuming it is temperature related.

Curious if you investigated it further, etc.

Thanks!

Josh
This red led on my Mac Pro usually shows memory over temperature. Usually happens in hot days when I’m using RAMDisk to compile things.
 

martyr

macrumors newbie
Jun 19, 2007
26
9
This red led on my Mac Pro usually shows memory over temperature. Usually happens in hot days when I’m using RAMDisk to compile things.
Interesting. It's definitely not hot in the room here - currently snowing in Calgary - but take a look at the "Relative to ProcHot" reading, along with all the other sensor readings and let me know what you think.



I'm thinking I might have to re-apply some thermal paste and may be tighten the heatsinks. Running two X5690s.

Thanks for your help, btw!
 
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tsialex

macrumors 604
Jun 13, 2016
7,836
8,473
Brazil
Interesting. It's definitely not hot in the room here - currently snowing in Calgary - but take a look at the "Relative to ProcHot" reading, along with all the other sensor readings and let me know what you think.



I'm thinking I might have to re-apply some thermal paste and may be tighten the heatsinks. Running two X5690s.

Thanks for your help, btw!
Really weird. You definitively have something wrong.
 

martyr

macrumors newbie
Jun 19, 2007
26
9
Really weird. You definitively have something wrong.
Okay, that's what I was thinking. I've been reading a lot about the Northbridge heatsink retainer clips breaking on these. The thermal paste might need replacing on the CPUs. And the CPU heatsinks might not be seated properly.

Bought this used by somebody that knows what they were doing but I haven't lifted the CPUs yet. Dealing with one issue at a time. Haha.

I'll try and remember to post back here and thanks for all the continued help.
 

expede

macrumors regular
Jan 15, 2018
203
54
Sweden
Hi!
This is what the "Apple Technician Guide say;

"These error LEDs are normally off. A red illuminated LED indicates the associated preocessor may be missing or in overtemp state (PRICHOT).




Best regards

EDIT: Saw that this an very old question. Sorry. He, he!! The question is very old.
/Per
 

martyr

macrumors newbie
Jun 19, 2007
26
9
I wanted to follow-up here.

I removed the CPU B heatsink and re-applied some $20 Cooler Master Nano thermal paste (the good stuff!) The good news is that this completely fixed the flashing red light. The value of "Relative to ProcHot" normalized and my fans started acting as normal as well.

My thinking is that there was not enough thermal paste, causing the processor to keep bumping up against the processor's limit. This, in turn, caused the motherboard to go into emergency mode and maxed out the intake and exhaust fans, even during idle after the temperatures had calmed down.

Fixing the red light and running the fans normally were huge wins for daily use of this bad boy. It's so quiet now. Just the GTX 980 Ti humming away that I gotta fix. I think I saw some additional Geekbench performance with the new thermal paste as well. Btw, I re-applied the same thermal compound to CPU A - I didn't want to neglect her.

So, that problem is solved.

Next what happened was that Slot 6 of my RAM was causing issues, not being recognized and showing the red LED on the motherboard. I ended up buying a new stick from OWC to replace the one in question but that didn't work either. I removed the CPU B again to see if I messed something up and I found that one of the gold "caps" on the CPU had fallen off and was now lodged in the base pins. Pictures below.

I managed to remove the piece lodged in the base pins but couldn't get the base pins realigned without a magnifying glass and a sewing needle. But, it still boots and gets a respectable 23000 on Geekbench so I put 3 sticks of 16GB in Slots 1, 2, 3 and 5. Packaged it up. And called it a day.

For now...

IMG_0169.jpg
IMG_0170.jpg
IMG_0164.jpg
IMG_0155.jpg
IMG_0156.jpg
 

Brian M

macrumors newbie
Nov 23, 2019
5
2
I’m having the same exact issues. I upgraded my processor and got no red light. I ran the Cinebench and it got a great score. I then noticed the red light. After panicking a bit I removed the processors and put in my old processors. I rebooted and now I’m getting red light. My ram slot five is now not showing . Ahhh help!!

Im not sure what else to do. I will try reapply with a higher quality thermal paste and see if that helps.

where u able to clear off the red light?Is there any danger if the red light continues? My fans are not going crazy either.
 

South Bend

macrumors newbie
Mar 17, 2005
5
0
Central California
I’m having the same exact issues. I upgraded my processor and got no red light. I ran the Cinebench and it got a great score. I then noticed the red light. After panicking a bit I removed the processors and put in my old processors. I rebooted and now I’m getting red light. My ram slot five is now not showing . Ahhh help!!

Im not sure what else to do. I will try reapply with a higher quality thermal paste and see if that helps.

where u able to clear off the red light?Is there any danger if the red light continues? My fans are not going crazy either.
Do you have a single processor Mac Pro or dual? is it a 2010?
 

South Bend

macrumors newbie
Mar 17, 2005
5
0
Central California
Yes it is Dual 2010
5,1 (not Flashed).


Everything seems to be working except the red light.
OK...we have the same Mac. I swapped out the two chips I had for 2 Xeon 5690 chips, and I also swapped the Graphics processor out for a Radeon VII. I have two red lights, and two DIMM slots are showing as empty. I am in the process of trying to figure this out and get rid of the red lights and the ram slots showing as empty when in fact there is ram in those slots. Maybe we can work together on this. Interested?
 

Brian M

macrumors newbie
Nov 23, 2019
5
2
OK...we have the same Mac. I swapped out the two chips I had for 2 Xeon 5690 chips, and I also swapped the Graphics processor out for a Radeon VII. I have two red lights, and two DIMM slots are showing as empty. I am in the process of trying to figure this out and get rid of the red lights and the ram slots showing as empty when in fact there is ram in those slots. Maybe we can work together on this. Interested?
i g0t my red light to go away by taking out two sticks of ram. i can’t fill up my ram but the light is gone.

I’d love to help. I’m narrowing it down to some possible causes

1. The head sink is either too loose or too tightened or not linEd up
2. The cpu is damaged, or the cpu insert is damaged.

im guessing heat sink is the cause. I really struggled with getting them lined up and tightened correctly.
- - Post merged: - -

 
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South Bend

macrumors newbie
Mar 17, 2005
5
0
Central California
Wow...that's great that the light is out! You can't fill up your ram? I have the same problem with ram. I can put ram in the slots, but it doesn't show up.

If you have the 2010 Mac Pro I think the heat sink screws have "stops" on them, so that you can only tighten them so much and then that's all. The screw will just suddenly stop turning, even when you are applying just a normal amount of pressure. When the screw stops turning, you're done!
 

Dahjxiii

macrumors newbie
Nov 30, 2019
3
0
Hey all! Pretty new here and did my best to exhaust all the forums but I can't seem to get to the bottom of it.

My issue is very similar to you guys -

Running macOS Mojave 10.14.6 on a 4,1 flashed to 5,1 cMP
2 x 3.46ghz 6-core Intel Xeon
32GB 1333 MHz DDR3
RX580 GPU


So my issue is, I was originally running 10.14.4 via DosDude's hacked method - running a slow 5870 powering 2 monitors and 2 x 2.26ghz.

I went ahead and followed @tsialex walkthrough for installing mojave via mac updates, doing a clean install of High-Sierra to clear the hacked install of Mojave. All seemed well, GPU and New CPU's running well but then ran into a red light on the CPU board and only showing 28GB instead of 32GB. Can't really place the cause since it's my first time dealing with it.

I reseated all the RAM, reseated the CPU's and the light went away, showed all 32GB of RAM - but then, about 10minutes in, the computer froze and restarted, and red light is back on along with only showing 28GB of RAM.

Issues that accompanied it is the CPU load, for something as simple as exporting 20 images to desktop from Lightroom, is 98%! That's new. RAM pressure is sky high as well - did a PRAM reset and it worked out, so don't have any screenshots of that - but hopefully someone can provide a bit of insight.

Provided a screenshot of where the light is showing up. It looks to line up with dsd706 but no idea that is either, so I could be wrong on that correlation.

Thanks in Advance!
 

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Cape Dave

macrumors 68000
Nov 16, 2012
1,962
1,106
Northeast
I sometimes suspect that 90% of all computer issues could be solved by removing CPU, cleaning, and reapplying QUALITY thermal paste properly. I think I am right :)
 

MacProRestoreGuy

macrumors newbie
Mar 2, 2020
20
0
Red light coming on CPU tray but all temps and RPM's look fine. I'm going to put on better quality thermal paste and see if it makes a difference. Thank you for all the suggestions.
 
Last edited:

MacProRestoreGuy

macrumors newbie
Mar 2, 2020
20
0
I wanted to follow-up here.

I removed the CPU B heatsink and re-applied some $20 Cooler Master Nano thermal paste (the good stuff!) The good news is that this completely fixed the flashing red light. The value of "Relative to ProcHot" normalized and my fans started acting as normal as well.

My thinking is that there was not enough thermal paste, causing the processor to keep bumping up against the processor's limit. This, in turn, caused the motherboard to go into emergency mode and maxed out the intake and exhaust fans, even during idle after the temperatures had calmed down.

Fixing the red light and running the fans normally were huge wins for daily use of this bad boy. It's so quiet now. Just the GTX 980 Ti humming away that I gotta fix. I think I saw some additional Geekbench performance with the new thermal paste as well. Btw, I re-applied the same thermal compound to CPU A - I didn't want to neglect her.

So, that problem is solved.

Next what happened was that Slot 6 of my RAM was causing issues, not being recognized and showing the red LED on the motherboard. I ended up buying a new stick from OWC to replace the one in question but that didn't work either. I removed the CPU B again to see if I messed something up and I found that one of the gold "caps" on the CPU had fallen off and was now lodged in the base pins. Pictures below.

I managed to remove the piece lodged in the base pins but couldn't get the base pins realigned without a magnifying glass and a sewing needle. But, it still boots and gets a respectable 23000 on Geekbench so I put 3 sticks of 16GB in Slots 1, 2, 3 and 5. Packaged it up. And called it a day.

For now...

View attachment 794201 View attachment 794202 View attachment 794203 View attachment 794204 View attachment 794205
Dental tools work good for these situations, IMO.
 
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