What do motherboards do?

[chalky16]

What does a high end motherboard do that a cheaper one doesn't? I'm only getting one graphics card so what does a more expensive one do for me that the cheaper one doesn't?

 

[DRagor]

One or more of following:
- more USB ports
- more SATA ports
- more RAM slots
- more power phases
- better sound card
- WiFi, Bluetooth
- second LAN controller
- more fan headers
- rgb headers
- more PCI slots (they are not only used for GPU)
and so on.

 

[JamesSneed]

Also chip sets come in to play like B250 vs Z270 Intel chip sets when comparing cheap vs expensive motherboards. Much of it is the same feature sets DRagor listed with one notable item is the lower end chip sets from Intel and AMD tend not to allow for overclocking.

https://rog.asus.com/articles/guides-pc-build/whats-the-difference-between-z270-h270-b250-and-h110-chipset-motherboards/
http://www.tomshardware.com/news/amd-am4-ryzen-chipsets,33806.html