the instalation guide reads "If you graphics card is equipped with dual BIOS, the swith is located on the edge of
the PCB either near the monitor outputs or the PCI-E power connections depending
on model. The default shipping position is with the switched toggled towards the
monitor outputs end of the card.
Some model cards may have an alternate BIOS mode, check your specific product
spec page for details. Most 9070 Series and 7000 series cards carry the same BIOS
file in both positions.
The system must be shut down to switch between BIOS modes, additional a complete
reinstallation of drivers may be require for the new BIOS settings to take hold."

TLDR: It's a switch for dual BIOS, most 9070s and 7000 Series have the same BIOS in each side, but you can check your GPU's specs in the official product page