Alright so I bought this card https://www.amazon.com/MSI-RTX-2080-GAMING-TRIO/dp/B07GHXQTGZ/ref=sr_1_3?s=electronics&ie=UTF8&qid=1544567643&sr=1-3&keywords=2080 I have ordered it and when I look on the back Minimum system requirements: 650 watts but I've looked at the same model on pc part picker and its TDP is 250 watts so whats the actual amount of power ill need.
Why don't you check the manufacturer's website?
If you look at the specifications at NVidia's website, you'll see that the nominal power consumption is around 225 W.
The official MSI website for that specific GPU says 300 W:
thanks I wasnt very sure it just confused me
FWIW, one of the reviewer website had it up to 335W with OC