USB BIOS settings?

[RangergOrd]

The BIOS settings for my Gigabyte MBd list three USB categaories that I cannot find any refernce to.
It's an AWARD BIOS and in the "Advanced Chipset Features":
1. USB ParkMode: Enable(set)/ Disable
2. USB Perf Mode: Compatible(set)/Moderate/Optimal/High
3. USB Read Requests From: non-ISO/ISO Queue(set)

Anyone know what these are and more importantly, what does changing them do?
Tried a couple of forums without success.