After some reluctance, Mwave decided to replace my card in store. This was after 1+ hours of testing and failing to replicate the issue (of course it only happens during certain games and after an arbitrary amount of time). They had FTW cards in stock, but I did not want to take the risk of it happening again when I live 3 hours away (was unsure if their current stock is still affected). So I upgraded to the Gigabyte Xtreme Water Cooling instead.
To anyone else having the same issue with their cards and getting pushback from the retailer, just make sure you have an RMA ticket from EVGA first.
Probs to EVGA Taiwan for the speedy response with an RMA number once emailed. Though in this case it was my own will and not accepting anything less than a refund or replacement that got me what I deserved in the end.