Unless you are experiencing technical issues, like crossfiring the same gpu's from different manufacturers for better compability by using the same bios.. DO NOT flash vbios! you could brick your card and you will gain exactly ZERO performance increase.
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Intel I7 3770K @ 4.5ghz, Cooler Master Hyper 212 Evo, Gigabyte Z77X-UD3H, Gigabyte HD7970 ghz edition, 4x4gb Kingston HyperX Beast 2133mhz, Seasonic Platinum 860, OCZ Vertex 4 128gb, WD Black 1TB, WD Green 3TB+1.5TB, ASUS Xonar Essence ST, ASUS VE278Q, Windows 3.11