You wont be getting 0.5 xmr per day with any single GPU .
Anyways the amd vega 64 do good on CryptoNight algo around 1400 h/s
amd 480/580 do around 700
I dont think nvidia is good for CryptoNight algo .
anyways using what to mine currents stats you need around 120000 h/s to get around 0.5 xmr a day and that means around 85x vega 64 or 170x rx 480/580s
Your math is wrong. You need approx 30'000 H/s for 0.5 XMR/day.
That's 20 Vega 64's (not 85).