never go cheap on the psu. nothing will work without it, and a lot of problems stem from the psu being too small or not delivering clean/stable power.
i wouldnt get anything below 550-650w that is platinum rated.
been there: replacing the cpu/motherboard/ram/gpu because i wanted to save "20" bucks on the psu...
and as said before, if you dont need large amount of storage (for now), go with a ssd.
example: netbook with win 7, 2gb ram with hdd took 2min to boot.
same unit with ssd :+30s.
dont waste money on higher clocked gpu.
EVERY 1070 with custom board/cooler will clock around 2Ghz.
use afterburner to raise power/temp limits to max, and the card will auto boost to max possible on that chip.
unless you play for money, going with 144Hz will "only" reduce latency, but introduce screen tearing.
a screen with gsync will run smoother, eliminate tearing, and get decent latency, and most likely be cheaper.
i have a lot of friends that own 120/144Hz screens, and all went back to 60fps with gsync enabled, saying its as smooth/smoother than running above 100fps.