820-3332 high spinning fans just after os is booted.

jadao

Member
This board had u8900 issue and was booting to black screen, it had also high fan spin before I even touched it.
I fixed the video issue by soldering and reflowing the U8900 ISL.
It is now displaying image but it has fans spinning very loud only after booting to OS.
I tested different internal ssd, diferent usb disks, different I/O board. It is not a trackpad/ts0p issue.
It passes ASD EFI and OS. On boot menu fans are quiet,
What am I missing? Could this still be an u8900 issue? Bios ?
thanks
 
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jadao

Member
Hi 2informaticos, I tried removing all cables including the camera cable and still making fan very high when mac Os is launched same with different os or usb drive or internal ssd.

please see attached picture or under this link image of sensors on Hardware Monitor, to me nothing seems strange except CPU package graphics with no reading...

https://www.dropbox.com/s/wiryi1indp..._6554.JPG?dl=0

Thanks
 

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2informaticos

Administrator
Staff member
Do you have original Apple Magsafe 2 85W charger?
On battery only, fans run high too?
Do the fans go to max instantly, or gradually increase after logged in?
 

jadao

Member
I am using only original 85W magsafe 2.
Yes same with only battery on.
it starts gradually after logged in.
if I close the lid laptop goes to sleep, when I open it back, few second good and then again will gradually increase to full blast fans.
 

2informaticos

Administrator
Staff member
Power supply voltage looks high; 18.5V is normal for 85W.
Try the machine using 60W charger; just for test.
However gradually speed fan inceasing point to temp issue.
 
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jadao

Member
Hi 2informaticos, thanks for your support, I tested with a 60W charger and have the same issue.

I tested also the 85W charger on a known identical board and it still report 20.4V however one big difference I found was for the GPU.
on the known working board GPU current sensor is only showing 0,07A. On the loud fan board Gpu sensor shows 6A.

Don?t know if it would be more ISL8900 issue or gpu as the board seems to get warmer then the known working.

I attached a picture of HardwareMonitor on the known working board.
 

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jadao

Member
SMC_GPU_HI_ISENSE is 0,46V on boot menu
When fan is not high.
It is 0,127V when OS is loaded and fan full blast.

Unfortunately I don?t have anymore the known working board to compare. Will report as soon as I have another one:(

I still need to check U/R5410 and circuit.

Will report asap.
thanks
 

jadao

Member
I am sure HWMonitor default at 13,60V because battery was missing. I didn?t bother with that as I had the same value with known good working board.
Will post values asked as soon as I am in front of the board.

So far the only obvious difference I noticed is the current gpu sensor.

thanks
 

jadao

Member
I got another 820-3332 and I compared again the values with Hardware Monitor,
here are the results:

Bad board
SMC_GPU_HI_ISENSE
0,46V on boot menu
0,127V when OS is loaded
GPU current: 6A

2nd Good board
SMC_GPU_HI_ISENSE
0,35V on boot menu
0,04v when OS is loaded
GPU current: 0.08A

First good board
GPU current:0.07A

All the boards are consistently displaying 13,60A for battery I think it?s just because it?s unplugged.
 

jadao

Member
Here are my findings:

Good board:
iGPU: GPU current 0,09A fans spin quiet
dGPU: GPU current 7.02A fans spin quiet

Bad board:
iGPU: GPU current 5,84A fans spins high
dGPU: GPU current 7.03A fans spin quiet

Now I am a little bit ashamed about something:
ssd was empty and I decided to install a fresh OS and it?s not doing the weired fan spinning loud.

Still a mistery why my daily used usb flash os or external usb hdd has this effect only on this board...
Maybe a matter of SMC, EFI, version that doesn?t like to boot os by usb and messing with iGPU/dGPU? Or a gmux switching issue?
 

2informaticos

Administrator
Staff member
"iGPU: GPU current 5,84A fans spins high"
Maybe iGPU is not really enabled.
GPU cannot consumes such high current in this case.

Do you mean machine runs fine now, with fresh instaled OSX on internal SSD?
 

jadao

Member
No finally machine still does'nt run fine..It looks like problem appear whenn it's on iGPU when I switch to Dgpu fan is quiet, when I switch back ti IGPU fan goes crazy...
 
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