I'm pretty sure Maxwell cards (GT 750, GTX 750 Ti, GTX 8xx, GTX 9xx) compress stuff before sending it through the memory bus, so they perform as if they had a higher memory bandwidth than they actually do. AMD have some cards which do this, too, but I'm pretty sure they deemed it unnecessary for their HBM cards (the Fury series).
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
