820-3332-a - Video problems when on dedicated GPU (high power mode)

Joesipaq

New member
Hello all,
I wanted to know if anyone has seen this issue before. A client came by with video problems. My first thought was the GPU Vcore, but how i have seen that is Video or No Video, not a glitchy video.

I have not poked around yet, as if it is a breaking solder joint, i know i could make it worse by probing it, or just the flex of taking the board out.

My other thought, is a RAM issue... I say this because just last week I cleaned out an older MBP that has most the plastic retainer worn off of the RAM slots (how i dont know) That computer had the same pixily issues from the moment of bootup (the white apple logo had some pixels out of place) and i am seeing that being a similar problem as to this one, but the screen taring and weirdness was not experienced on the other ram issue mbp.

Here is a link to what the screen is up to now. https://youtu.be/q4rptvKRiT4 and https://youtu.be/uA4FfXsFg-s
Here is a closer picture of the screen funkieness IMG_20190122_154824.jpg
 
Last edited:

Joesipaq

New member
FYI i am waiting on an approval for a flat rate motherboard repair from the client, when it is approved, I will really start to dig into the board starting with resoldering our friend GPU_Vcore chip. gmux? its been a while since ive seen one of these so i might have just assumed the gender of gpu vcore
 

Joesipaq

New member
I just verified that it is not an OS issue, I booted off of a clean install external SSD. When running Google earth Pro, artifact is present, when closing it and unplugging the power cord (automatic video card switching is enabled) the artifacts go away 100%
 

2informaticos

Moderator
Staff member
Reflow (resolder), change U8900, in this order.
Reflow should be good enough...
If no result, then reflow GMUX too.
 

Joesipaq

New member
I have reflown U8900, no difference, will now change it. Need to go find a doaner board. Just to verify, the GMUX is U9100?
 
Last edited:

Joesipaq

New member
What is the difference between the Analog MUX and the DPMUX? besides one is or analog lol.
I honestly have not tried an external monitor yet as when switching video cards i can reproduce the error every time. Tomorrow i will give it a try though.
 

2informaticos

Moderator
Staff member
U9150 switches only video lines between iGPU and Nvidia GPU for internal LCD.
Backlight is still controlled by DPMUX however.
DPMUX also controls all power rails for Nvidia GPU.
 

Joesipaq

New member
I just tested it on an external monitor and yes, i get the same issue.

So when you suggested to reflow the GMUX which one should i reflow?
 

Joesipaq

New member
I have not re-flown U9100 yet, as practicing i havn't gotten the temp right yet, and pop-corned a chip... Oops. Got 2 more boards to learn on before this one. I am thinking though, it it is a nVRAM issue, and i see results, most likely wouldnt it be a temporary solution due to just heating the SNOT out of the nvram by proximity? If this is a temp solution, id rather not offer it to my client.

Has there been a bypass created for this board yet? Or is that something i should try to crunch out of the schematics to copy the other ones floating around?
 

dukefawks

Administrator
VRAM, GPU or trace issue inside the board. Inspect GPU VRAM area for knocked off components too. This has nothing to do with any of the MUXes. Don't reball/reflow VRAM or GPU, just replace them.
 

Joesipaq

New member
Thanks for the heads up Duke. VRAM i think would be simple enough to change out, but the GPU, i haven't done that before and have seen the videos of that east machiene to do bga on gpus, do i need soething like that to correctly change out the gup?
Where would you source the vram and gup from?
 

dukefawks

Administrator
GPU would need a decent rework machine yes. VRAM are not something that normally goes bad so getting them off Ebay/Ali from China should be ok. I would try the VRAM first as these GPUs don't tend to go bad.

You did make sure the problem only exists when using the NVIDIA GPU? Problem should not be there when on Intel of course. Run a 3D test like "heaven" to test.
 

Joesipaq

New member
I would say the odd video issues are consistent with what i have seen in bad ram. Thanks Duke.
I know there is a sub fourm for Tools, but to ask you directly, do you have any experience with what would be a decent rework machine 240v for casual stuff? I don't think ill get hardcore into bga rework - but who knows
 
Top