The two USB 3.0 ports are not recognized by my AM3970 most of the time

The USB 3.0 ports were working fine until several months ago. Now occasionally even when they are discovered and working fine after drivers are installed, I will lose them again in the next reboot. I have the version of chipset driver and Etron USB Controller drivers, which are listed on Acer site, installed. When they are working (99% of the time), the ports are shown as 'not connected' in Device Manager. I used to hibernate the desktop and only reboot it two or three times a week. Occasionally it could not come out from hibernation and required a reboot. Under this circumstance, it would find the ports and install the driver again but was lost after the next reboot. Since then I have installed a SSD and no longer have hibernation enabled. However, the USB 3.0 issue still exists. Any help will be much appreciated!