Retina MacBook Pro 15" (Late 2013, 820-3787) random GPU related shutdowns

jpc

New member
Hi,

I have an issue with the Retina MacBook Pro 15" (Late 2013, 820-3787) with DG which shutdowns all the time after 10-15 minutes of use. The screen (does not matter if internal LCD or HDMI display) goes blank for a couple of seconds while the fans start blowing faster and afterwards the machine shuts down completely. Only very rarely it does not shut down on its own or it shuts down immediately without blowing fans.

What I have tried so far:
1. Forcing it to use only the discreet or integrated GPU – does not help.
2. Downgrading and upgrading the system (between whatever it shipped with, Sierra and High Sierra) – no significant difference.
3. Booting Windows 10 from an external drive which worked on this machine before – hangs with a black screen on boot.
4. Recovery, Time Machine recovery, Safe mode – all work perfectly.
5. memtest86+ 7 full cycles over night – no errors, no hangs.
6. Checked various voltages (PP1V5R1V35_GPU_REG, PP1V05_S0GPU_REG, PPVCORE_S0_GFX_REG, PPBUS_G3H, PPVCC_S0_CPU_REG ) with a multimeter while the computer was running correctly and while it was hanging before it goes dark – nothing out of ordinary. I have also measured currents and checked that both phases of the GPU power converter work and that one of them turns off when GPU is idling.

There is one I can do to prevent the computer from hanging – keep the Nvidia GPU loaded. GPUtest 0.7.0 works pretty well for this just by rendering a colorful triangle as fast as it can. While the framerate and CPU usage does change if the window is visible on screen or hidden behind other windows but it keeps the computer from hanging either way. The GPU Vcore is reported as 0.88V while the program is running (this reflects the [1.5V nominal] VCORE voltage).

The system is not internally damaged in any visible way. Nothing was spilled on it. I did not check the inaccessible side of the logic board yet. I also did not check the voltages with an oscilloscope yet.

Have anybody ever encountered such an issue? Does anybody have any ideas what I could check next?
 

jpc

New member
No, no error reports, kernel panics or anything else in the logs. I get a blank screen and a shut down after a few seconds. Sometimes it gets stuck with the the blank screen and fans blowing for longer. Either way I have to press the power button to get it to start again.

When I am connected via HDMI the display shows the image instead of a blank screen. It may be that only backlight turns of on the internal screen while the image remains. I will try to verify this later.

I start to suspect that I don't have to load the Nvidia GPU specifically. Yesterday I tried to run the GpuTest on the Iris Pro and also seemed to prevent the shutdowns. I will test this further and also try loading only the CPU with prime sieve or something like that.
 

jpc

New member
Ok, I verified that the hanging has nothing to do with the Nvidia and everything to do with the CPU. I am running Prime95 for 2 days now and Nvidia is completely powered down. While I was running GPUTest I would render something very simple with lots of FPS and this would also load the CPU a lot.

So I guess I should focus on the CPU power supply. Does anybody have any tips to share?
 

dukefawks

Administrator
Nope, I have not figured out this issue with 3662 and 3787 boards yet. Resolder U9300 first to rule that out.
 

dukefawks

Administrator
Possible fix is to replace the CPU FETs. Seems to work no returns yet. Get them new though, don't pull them off donors.
 
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