Eu instalei recentemente o Ubuntu 16.04 e, desde então, nenhuma das minhas portas USB 2.0 tem funcionado, mas minhas portas USB 3.0 estão funcionando (na frente e atrás). Todas as portas funcionaram na minha instalação anterior do Fedora. Os dispositivos que estou conectando são de baixa potência: um receptor para meu mouse, uma webcam e um microfone.
Placa-mãe: Gigabyte 990FXA-UD3
$ dmidecode
Handle 0x0012, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB1
External Connector Type: Access Bus (USB)
Port Type: USB
Handle 0x0013, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB2
External Connector Type: Access Bus (USB)
Port Type: USB
Handle 0x0014, DMI type 8, 9 bytes
Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB3
External Connector Type: Access Bus (USB)
Port Type: USB
$ lspci
00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:12.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller
00:13.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:13.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller
00:14.5 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI2 Controller
00:16.0 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB OHCI0 Controller
00:16.2 USB controller: Advanced Micro Devices, Inc. [AMD/ATI] SB7x0/SB8x0/SB9x0 USB EHCI Controller