Loose solder ball seems the most plausible reason.

I could definitely see that.  
 
I did notice that both PCB's have different markings on them.  That would lead me to believe that they were fabricating in two different factories, which would reduce other possibilities.  Hopefully these are extremely limited cases and are unique to these users.  

Learn how to manage your temps with Precision x1, even if it still in beta...definitively not for kids this device!! RIP human brain

MuXuSS
Learn how to manage your temps with Precision x1, even if it still in beta...definitively not for kids this device!! RIP human brain

Yes, RIP human brain and with that said, you still shouldn't have to endure this with all the protections put in place, especially at this price range.

But have you used benchmark like furmark?

Would be funny if it was the RGB controller letting the smoke out of those components

Here is Buildzoid's "RTX 2080 Ti FE PCB Analysis" video, you can get a look at what is in the area of the blow out
 

crunching and surfing  my virgin 11G-P4-2383-KR
 
RTX 2080 Ti XC ULTRA  backplate reads with IR therm the burned area 38c and rest 32c  
 
looks EVGA had ran this card for never had the new smell of PCB out of the box, I guess their having issues with reference PCB vendor for was a delay in shipping to weed out the bad ones. 
glad they made sure for I run 7/24 or would be another Fire liability like Pacific Gas & Electric over California's Fire disaster 2018 or  was it EK water block kit
 

May very well be current overflow from a chip getting too hot and destroying itself, and taking everything along with it in a dead short. The burned area is I believe part of the power supply circuitry for RAM.

santa_ryan
May very well be current overflow from a chip getting too hot and destroying itself, and taking everything along with it in a dead short. The burned area is I believe part of the power supply circuitry for RAM.

its not.