If I am buying all the components to build a new computer, do I need enclosures or mounting kits, or motherboard trays for the components to work successfully? Or do the components themselves come with mountings/screws?
More aboutmounting kits
most cases come with mounting screws for hard drives. SSDs, being 2.5" and 1.8" in size, often need specialized mounting kits, although some cases will accomodate them as well