I don't even know what is low power usb but all the same the least speed was 6MB/sec for flash drives, as for external hard drives I don't remember the speed before the upgrading of ram. After the upgrade the speed for flash drives starts at least 8MB/sec and then it reduces gradually to 3MB/sec if I'm not copying anything at the same time. The worse thing is even at 3MB/sec speed, it's not continues, it stops occasionally which makes copying very very boring. And for the occasional stopping it happens to external HDD too.
The following are transfer rates I have observed:
1. Between internal drives: from 20MB/sec to 51MB/sec.
2. From internal drives to USB HDD: from 13MB/sec to 15MB/sec
3. From internal drives to Flash drives: Starts from 10MB/sec and drops gradually to 3MB/sec.
I'm not using windows XP is windows 7.
1. For internal drives, if it is SATA II, then its ok.
2. For USB HDD, it should be @ 50mb/s. Is your usb hdd is too old or you didnt plug another usb jack for auxiliary power?
3. Sometimes flash drive get slow when its old and reduce speed.
If you think its happen from any sudden action, then you can give a clean installation of os. Mobo USB port never do this slow. I use 7 years old mobo which is still faster as before. Love my gigabyte mobo.
Did you check from new account? You can at least try.
Installing clean win7 is it not the same as installing fresh win7 or new win7? Because for all the videos I've watch from youtube, it seems to like they all the same, just that they do no partition. If what I'm saying is true then I've install two new win7 but the problem seems not be solved.