|How did you determine only two ports were working as 2.0?|
They are all USB 2.0 ports barring perhaps some hardware failure. Device manager isn't going to list each port. The line that has 'enhanced' in it is 2.0 support for all the ports. The other stuff listed there is simply what's necessary for general USB support and backwards compatibility to 1.1 devices,
(Note that if you've added a USB card then device manager will list its setup separately)
Check this old thread and my # 3 there:
Ding dong the witch is dead. . . .