HardOCP points out that since May 25, 2018, EVGA requires the original invoice in order to make a warranty claim. Without a valid proof of purchase from a reseller, EVGA is no longer providing warranty to owners who bought EVGA products on the second-hand market.
On the EVGA forums, a moderator clarified that the original owner can give a copy of their invoice to the second owner. This qualifies as proof of purchase.
The reason for the change is simple. With GPU cryptocurrency mining going out of fashion once again, EVGA must be wary of a potential flood of claims.