2x8 is ideal cause your already going to be on that 8gb threshold.
Also cheaper to buy more RAM now cause you can double up for only 50% more.
Oc'ing works far better when 2 dimms are populated over 4 dimms.
Get the 620 watt seasonic PSU thats fully modular for a few bucks more.
Don't buy retail windows, shits 5$ for OEM key on ebay
SSD to small for having games on it
Much better build here and teh additional cost is from the ram rest is negated buy removing windows retail key.
https://pcpartpicker.com/list/NWsVWD