Save, or spend your money elsewhere. Onboard sound has come a long ways from the onboard models of 10 years ago.
Unless you're one of those audiophiles, it's largely a waste.
Back on my old Asus Z77 motherboard, I noticed a difference in sound quality between it and the Xonar DX I have.
Then I later moved to an X299 Prime, and the card wasn't necessary anymore; it made cable management very slightly easier too.
But then I made an 'oopsie' during maintenance and knocked off some kind of capacitor/transistor/whatever and now sound only plays through 1 of the 2 Klipsch 2.1 speakers.
Good thing I still had the old sound card lying around, as it saved me from possibly having to buy a new motherboard...