Usb adapter ?

[borden5]

so i'm looking for upgrade my case but the case i want have usb 3.0 20 pin header but the thing is my motherboard doesn't support usb 3.0 ,so how do i convert this usb 3.0 into 2.0 so i can connect it directly into my mobo ? and i don't want to have usb 3.0 sitting in front panel and be useless.
http://www.techpowerup.com/reviews/Corsair/Carbide_400R/images/contentparts.jpg
and im looking to buy 1 of these adapter in the picture but i can't seem to find it anywhere. Is there any way to go around this ?

 

[borden5]

I don't quite get what you mean by sell it