garbled image on 3332 board after U8900 fix

[captainmac]

This board came in for the all-too-common U8900 issue: upon arrival the machine worked fine, but would crash once the board switched from Integrated to Dedicated GPU (the typical MUX issue).
I have redone the solder on U8900, but after reassembly, the screen is showing distorted/garbled image. I have tested with another compatible screen, but the issue is the same there.
See my attached image for what i mean by distorted/garbled image.
Any ideas what may cause this issue? I have triple-checked the soldering on U8900 and its surrounding components: all looks flawless.
Any ideas where to start chasin this issue?

 

[captainmac]

i should also mention that i have swapped U8900 for another chip from a donor; but unfortunately, the issue remains the same.
I have inspected the board for any knocked off components but no dice..

 

[2informaticos]

Image problem may be caused by GPU, or VRAM.
Maybe a BGA chip from graphics area reacted to hot air.

 

[captainmac]

Yes, you were right.. disabled the GPU with my Medusa, and the issue is gone.. Dammit, this is a no-fix then.

 

[2informaticos]

Is an old laptop.
The client should understand that using only iGPU is good enough.