820-3332-A - MBP 15" 2012 Retina - Dead GPU??

[Alan.L]

someone used a heat gun on the GPU poor little board

The internal display is not working, no backlight, no picture.
i get video on the external display, also i get some kernel panic reports sometimes, apps like Chess and Heaven won't open.
it seems like GPU is not turning on in OSX but its using the intel.

I've re-flowed the U8900 with new solder already but haven't try replace.

can i confirm if the GPU is dead or do i have a bad U8900 ?


smc_lid = 3.4v
gpuvcore_en = 3.2v

 

[dukefawks]

Judging by the green shit they also used Chine battery acid flux. Is GPU shorted? This will probably end up with pulling and recalling the GPU and VRAM.

Also I'm pretty sure the Thunderbolt port only works through the Nvidia GPU, so check if the GPU is even detected by OSX

 

[Alan.L]

Yes, osx can see the Nvidia GPU but it doesnt use it. When i try to run GPU apps, it just wont open.Gfxcardstaus wont let me select Nvidia.

 

[dukefawks]

I bet it is the shitty Chinese battery acid that got under the GPU and possible other chips in the area. Clean all that crap up and add some real flux and try to clear all the acid from under the chips with some heat and flux.

 

[Alan.L]

replaced U8900, cleaning up GPU area, used real flux with some heat and last run thru USC and still didn't work.

would GPU reball work or need a replacement GPU chip?

 

[dukefawks]

I would reball first. Also check for missing or damaged resistors/caps around the GPU. It could also be a MUX problem if flux got under that chip too. Is GPU Vcore present now?

 

[Alan.L]

PPvcore_gpu = 0.9v
L8360 = 1.36v
PP3V3_S0GPU = 3.3

i'v replaced u9100, external still working, ASD still failed same test.

 

[dukefawks]

Put another GPU on there and inspect for missing components. I dunno man, fucked up boards like these are always a huge waste of time.