New
#21
Case is clean and clear of DUST?
Your motherboard is screwed down to the case (aka. grounded) properly.
Southbridge has a heatsink and/or fan that is working (if applicable), the Southbridge handles USB functioning.... maybe see if new driver is available, although you probably did that already, be tempted to use an old version for troubleshooting/testing, too. Sorry, this is over most users' heads. :)
Specifically around anything related to the Universal Serial Bus fare? Or the cable to the extra USB ports in your case (top side and/or front, and sometimes found via a slot/bracket in the back) connected at the motherboard, fully snug?