2019 A2141 model Mac Pro question on logic board components

Those spots are good examples of corrosion from liquid damage. In fact, in the second photo you can see the outline of a liquid stain on the black area. Did you examine the inside of the Bottom Case to see if you see any liquid residue trails? Water doesn't leave much (if any) residue trails though.

FYI, it looks like you may have one or two chips near that corroded area which likely would need replaced or at least reflowed since I would expect their solder balls have been corroded & weakened, but they have solder balls beneath the chip which makes replacing them tricky. Who knows what things are like on the other side of the board as well.

Keep in mind the Apple MLBs are like huge heatsinks so you will need to preheat the area with a hot air station....expect the smaller components to move around as well since there will be some collateral "damage" so you will most likely need to reposition some nearby components as well.

Good luck with your project. Interested to see how it turns out if you go through with it.

Yeah, it surprises me too how one spot in the center of the laptop can have corrosion with no other signs, although like I said, water doesn't usually leave a residue trail.

Unfortunately if you replace the MLB yourself (except for an official Apple Self Repair program....I don't think that is available for a 2019 model), or have any unofficial repair, then you may discover the Lid Angle Sensor will no longer function because it is paired to the original Logic Board. This means closing the Display lid won't cause your laptop to sleep anymore. You will also lose the ability for using a fingerprint to unlock the Mac although the TouchID will still work as a simple power button. I'm not sure what other functional issues you may encounter since many of the parts are paired with the Logic Board.

US$400 is nearly half the price of an entry-level MacBook Air. Good for all but maybe editing Videos.

¿Are you sure you need a rite-of-passage kind of repair in your life right now?

A T2-equipped board that was not properly 'cleared' of its previous owner's information may end up not being usable, at all.

<<. I don't like the idea of a previous owner's information on a computer. >>

it is MUCH more onerous than that. If the previous information was not cleared, you can't install -- well, anything -- because you are not the Admin.

We are using more and more reports of eBay sales where the seller did not prepare the Mac for sale, and when it arrives, it can NOT be changed.