There are many possible ways to implement eFuses in silicon, such as NOR flash without the erase hardware. Starts in the 1 state, you can program it to 0, but y

There are many possible ways to implement eFuses in silicon, such as NOR flash without the erase hardware. Starts in the 1 state, you can program it to 0, but you can't ever erase it back to 1 without exposing the silicon to UV. But the original IBM implementation was based on "resisters" which were physically damaged by passing too much current through them. Technically it's not "burning", as there is no smoke or combustion. Instead it's taking advantage of the electromigration side effect. But blowing is the closest analogy, the silicon is irreversibly damaged, due to too much current. You can read more here: http://paris.utdallas.edu/ssiri08/Tonti_SSIRI_eFuse_V2.pdf http://paris.utdallas.edu/ssiri08/Tonti_SSIRI_eFuse_V2.pdf I have no idea which technology Nvidia used to implement their eFuses.