Check the make of your motherboard. I have a Gigabyte motherboard and was able to download a utility that increased the power to my USB 3.0 ports and let me charge the iPad.
I think Asus motherboards have a similar utility.![]()
Based on my iTunes bills, mine is charging me just fine.
On my iMac, it says not charging and hit 25% overnight. Thought maybe that was only due to the facet that my desktop goes to sleep at night.