GPU issue (update Bios Drivers?)

[Izaakhallows]

So I bought this Gigabyte GTX 780 OC over EBay (supposedly brand new). I placed the card into my machine and the card worked perfectly fine. I then downloaded the latest drivers from the official NVidia website. Half way through the installation (it got up to installing 3d stuff..) the screen went black for a split second and then the PC rebooted. This only started when installing the drivers. The machine has a clean install of windows 8 64 bit with no other drivers or nothing like that so that rules out conflict issues. So I got told that maybe the GPU bios were "out of date" I did look on the card and it said "Rev 1.0". So how am I meant to update the GPU Bio?
My specs:

MotherBoard - ASUS Sabertooth z87
CPU - i5 4690k
CPU Cooler - h100i
PSU - EVGA 750w gold
RAM - 2x4GB corsair vengeance 1600

Thank you in advance.