Hi all, I want to buy a new computer

I will game on a 34inch 21:9 1440p 144hz monitor and will have 2 1080p 24inch monitor too

I have about 3k$ canadian money budget xd
I would like to have a gtx 1080

What thing do i need there is so much motherboard/ram/etc... at about the same price I just dont know
which one to pick...
Btw english is not my primary language sry for mistake....