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As I needed more USB ports on my GA-EX58-UD5 ( my tower requiert 4 * USB  + card reader with 2 * USB ports + 1 side has taken the floppy drive) I added an adapter with 8 ports NZXT as this : 
http://www.docmicro.com/pieces/description.php?numpiece=8677 And yesterday trying to connect a USB 2.5 inch external drive i was surprised to receive an error message from Windows saying the port was 
working in USB 1 .... not for all the USB ports but with only 2
I have complained about the NZXT adapter (i replace with another without shutdown my computer  ) and same problem  
Finally I replace with the old NZXT adapter , i reboot the computer , i make default in the BIOS setup , i reprogam my options (  sata .. ) and everything works again normally after  
Strange and mysterious! 
Pierre