It's BIOS switch. I think 1 is BIOS you can reflash, and 2 is original BIOS you can not change. A small help to people that like to overclock their cards.
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Intel i7 2600K @ 4.4GHz, Asus Maximus V GENE, Asus HD7970 @ 1050MHz, x4 4GB Corsair Vengeance Red @ 2133MHz, OCZ SSD Vertex 4 and 3, Corsair H80i, Corsair AX850 850W, Lian-Li PC-60FNWX, NZXT HUE