how would i do the win 10 when don't have license key
Buy a license key. Cheaper.
how about the same psu but in 650w version
Yes that would be fine, although I'd probably lean towards this one given the price. The money saved on this and Windows could then be put towards a better monitor. One of these perhaps...
AOC AGON AG271QG
DELL S2716DG
Acer Predator XB271HUAbmiprz
Trust me, you will appreciate the difference between 1080p and 1440p... it's a fantastic upgrade. And as mentioned, you're wasting a 1080 on 24" 1080p screen.