Look for german sellers on eBay - I won't say the nicknames, but you will easily find them.
An example:
Previously I got some reference ASUS GTX 980Ti from some private seller from UK flashed with wrong EVGA SC+ rom with OC speeds, core clock was about 100 MHz too high for it - as a result, card was overheating like crazy and had noisy fans. Also there was no way to dump rom from it or reflash it back to PC rom. It showed "ROM reading on this device is not supported". I was able to downlock the core under Windows with EVGA Precision X, but under macOS that was a nightmare.
Now I got original MVC card which works great. Rom revision matches, clocks are fine and it's super silent and cool despite hot summer days.
An example:
Previously I got some reference ASUS GTX 980Ti from some private seller from UK flashed with wrong EVGA SC+ rom with OC speeds, core clock was about 100 MHz too high for it - as a result, card was overheating like crazy and had noisy fans. Also there was no way to dump rom from it or reflash it back to PC rom. It showed "ROM reading on this device is not supported". I was able to downlock the core under Windows with EVGA Precision X, but under macOS that was a nightmare.
Now I got original MVC card which works great. Rom revision matches, clocks are fine and it's super silent and cool despite hot summer days.