Recommended PSU for this build

Hi guys, So I have been saving up to buy an new RTX 3080 Ti/ 3080 (whichever is cheaper) & wanted to upgrade my PSU from a Gigabyte G750H to a 850w PSU as well to have enough power headroom. I am having an Intel Core i7-8700K with MSI Z370-A Pro motherboard. PC details are mentioned below in...

I want to upgrade from 8gb of RAM to 16gb. This is the motherboard i'm using: Asus P8z77-V LK Motherboard (ATX LG1155) and the RAM: G-Skill 8gb (2x4) DDR3-1600 I was thinking of buying this...