being that's a older board and I assume a older psu ? I have seen guys claim there older psu did not work out with these cards and replaced with a new psu and all was fine ?? [was not due to the watts] ?
these newer cards and older chipset boards can be funny ''Update. It was definitely the Power supply''
http://forums.evga.com/GTX-980-Ti-Rebooting-Computer-m2401909.aspx
also did you format the usb stick correctly ??
just be sure the bios is for ''your board'' if you workaround and force flash the wrong one it maybe all over ??
contact asus support to see what they say ??
about what you said about calvin7 thing
go to asus global and you get this
http://www.asus.com/us/Motherboards/Intel-platform-Products/
http://www.asus.com/us/Motherboards/P8Z77V_PROTHUNDERBOLT/
then do it at asus U.S.A
https://www.asus.com/us/Motherboards/P8Z77V_PRO/
one got 11 updates one got 10 but all numbered the same like if there the same bios ?? wow
things like that is why my ''LAST'' asus was my ''LAST'' asus
maybe if you go to asus timbucktoo you may find another completely different p8z77-v pro ??
like me maybe go with a board company that offers straight forward support ??
my example how asus is
my board
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131736
now do you see it at asus to get support ??
https://www.asus.com/us/Motherboards/AMD-platform-Products/
nope just the rev2 and up they just left us holding the bag and dropped it or I got to do a lot of hunting around world wide to fine it ?? no thanks / and in the trash..
good luck