Question about 820-2850 MUX

[SMMRepair]

I have a customer who sent in a board saying that it crashed while opening Chrome (which is eerily similarly to another thread here recently); he said it will crash or freeze when overloaded. Board passes ASD just fine, and I will be replacing C9560 as usual. My questions are:

1. Is the 820-2850 MUX chip as common to develop cracked balls as it is on the 820-2610? I've had ~10 2610 boards in the past that needed to have the MUX chip reflowed due to cutting off and/or video issues on boot. Is the 2850 MUX also susceptible to cracked balls? Considering if I should reflow this one for good measure, or just leave it be.

2. I see a lot of warnings about reflowing the MUX on the 2850 (corner gel/epoxy getting under the chip and necessitating a reball); is it more likely to fuck up due to the corner gel than the 2610 MUX? I've reflowed tons of the 2610 GMUX chips (I do it every time I replace C7771, just for good measure). Is there something about the MUX chip on the 2850 that makes it more difficult to properly reflow?

3. Is it possible for the MUX to be responsible for the freezing/shut-downs even if it passes ASD?

I don't take many 2850's, but I'm doing this as a favor for a good customer, and want to send him back a board that's as reliable as I can make it.

Thanks!

 

[dukefawks]

MUX will not crash the system, don't touch it.

 

[SMMRepair]

Excellent, thank you duke.

What will be the symptoms of a MUX failure/cracked balls on the 2850? No video at all? LCD going black during use, etc? The board will work, but then the LCD go black after the LCD freezes for a few seconds. So in other words, the cursor will freeze, then after about 5 seconds, the LCD goes black. Keyboard backlight still on.

Does this sound like the MUX, or the CPU/GPU failing?

 

[dukefawks]

MUX will cause lines and distortion sometimes intermittent black screen, but system will not crash or reboot.