The Physically Unclonable Functions Found in standard PC Components Project, or PUFFIN, say that every GPU has a unique and defining set of characteristics that make each GPU as unique and individual as a snowflake or a fingerprint.
These differences are known as a physical unclonable functions (PUF); they can only be detected by software and by knowing where to look. This is how the PUFFIN group found the uniqueness to GPU memory in the first place, since it was looking for PUFs....
What this means is the 0s and 1s of SRAM have a unique arrangement to each GPU — which enables your GPU to become your authenticator. A WoW gamer won't need the separate physical authenticator any more, as her GPU can handle authentication for them.
In this article, Andy Patrizio speaks with several experts about the advantages and disadvantages of GPUs for two-factor authentication. Though, he points out, the research is still underway."