the asus strix gtx 960 IS oem
i maybe you ar thinking about reference cards?
Reference:
original design by nvidia specif specs
OEM by asus:
OEM by gigabyte
OEM by evga
Reference(original Nvidia design +specs) are first made and controlled by nvidia, they dictate how and what, nothing is left out of control, the manufacturer must follow these exactly
OEM, a manufacturer "takes" the design and gpu chip by nvida (they buy teh chip from nvida) but use their own "materials", quality, design, settings and such, the manufacture decide themselves and can do pretty much what they want, including making and selling you a GPU with wrong/last years models firmware to save money, if they chose and want
so in short, Reference=original=fixed build and fixed quality, manufacturer must "obey" nvidia
OEM= 99% of cards from stores, manufacturer decide build, design and quality and everything they want except the GPU chip itself(they buy that from Nvidia)