820-4924 Graphics Issue

[iambehr]

Hello,

820-4924 that will not boot - once the loading bar is 1/4 there are graphical artifacts in various colors and it hangs.
There was liquid damage that appeared to be minor, corrosion had eaten pin 13 of U1900, so replaced that chip, and there did not appear to be any other damage.
It will run the internal diagnostics and show no issues.

Anyone have any ideas?

 

[iambehr]

No Title

 

[aprendiz]

water damage somewhere, maybe under CPU or RAM...

 

[iambehr]

I have cleaned several times in the UC with no change. I don't want to pull ram chips off to look for issues.
Could this be a system clock issue? It will option boot and run EFI diagnostics. It will even boot tot the filevault unlock screen, it tanks after it actually boots OS.
Could this be a bios issue?

 

[Gurmon]

I'm with aprendiz on this one.

I've not come across BIOS issues causing this type of problem. I'd even say reflow the SMC with a good flux.

 

[Alan.L]

try perform a memtest86