I assure you, that is not a two-color silkscreen. The green NVIDIA 'eye' logo is much more likely a second manufacturing process (confusingly also a silkscreen

I assure you, that is not a two-color silkscreen. The green NVIDIA 'eye' logo is much more likely a second manufacturing process (confusingly also a silkscreen or pad printing process) that was done after the boards were received from the fab, or drop-shipped to a screenprinting company. I would be very, very surprised if the green eye logo was done in-house at the fab.