Really kind of sad that this is called making your own computer.
So system 76 is going to go to Foxconn, ASUS, MSI or some other OEM and have them make laptops for them. For desktops they will probably make their own case and go to Gigabyte, ASUS, ASUS or some other OEM and buy a motherboard.
It used to be that "making" your own computer actually made the CPU. Companies like DEC, CDC, IBM, Data General, Ti, HP and so one all made their own CPUs sometimes several different models.
So IC based CPUs came along. Then making your own computer meant making the motherboard and often the OS. Kaypro, Atari, Commodore, RadioShack, and so on.
Today it means making the case.
The only real computer companies left in the none mobile world seem to be IBM and Sun. Maybe Apple, HP, and Dell if you take the making your own motherboards as being good enough. The rest are just putting stuff in boxes