The USB issue is a little more complex than has often been portrayed. Disabling Legacy Support in the BIOS could solve any USB problems. But Intel has this caveat on its website:
"For your USB keyboard or mouse to work with MS-DOS-based utilities and non-Windows* modes, your computer must have USB Legacy Support enabled in the BIOS. USB Legacy Support allows the BIOS to interact with a USB keyboard, and in limited cases, a USB mouse. If USB Legacy Support is disabled in the BIOS, you will not be able to use your USB mouse or keyboard in any of the following situations:
Running your computer in Safe mode.
Using a Windows Startup menu.
Starting your computer in MS-DOS mode (instead of opening a MS-DOS session from Windows).
Starting your computer from a floppy disk or leaving a floppy disk in the drive when you turn on or restart your computer.
Windows "blue screen" errors that ask you to "Press any key to continue".
Responding to ScanDisk and other messages during the start-up sequence.
Editing or upgrading the BIOS.
Entering a BIOS password. "
The Asus BIOS gives you the option of setting Legacy Support to Auto, an option I think few people have tried.
If you have USB 2.0 devices that are not working properly, the first thing you should do is check the Device Manager. There should be a "USB2 Enhanced Host Controller" under Universal Serial Bus Controllers. If it's not there, then you may have problems. Apparently Service Pack-1 does not always correctly identify the USB controller on the 875P chipset. There are various ways to fix the problem. One solution is to delete all the USB host controllers in the Device Manager and reboot. The auto-detect function will kick in and hopefully you will see the USB2 controller in the Device Manager. Also, in the BIOS, the USB 2.0 Controller should be enabled and the Controller Mode set to HiSpeed.
"For your USB keyboard or mouse to work with MS-DOS-based utilities and non-Windows* modes, your computer must have USB Legacy Support enabled in the BIOS. USB Legacy Support allows the BIOS to interact with a USB keyboard, and in limited cases, a USB mouse. If USB Legacy Support is disabled in the BIOS, you will not be able to use your USB mouse or keyboard in any of the following situations:
Running your computer in Safe mode.
Using a Windows Startup menu.
Starting your computer in MS-DOS mode (instead of opening a MS-DOS session from Windows).
Starting your computer from a floppy disk or leaving a floppy disk in the drive when you turn on or restart your computer.
Windows "blue screen" errors that ask you to "Press any key to continue".
Responding to ScanDisk and other messages during the start-up sequence.
Editing or upgrading the BIOS.
Entering a BIOS password. "
The Asus BIOS gives you the option of setting Legacy Support to Auto, an option I think few people have tried.
If you have USB 2.0 devices that are not working properly, the first thing you should do is check the Device Manager. There should be a "USB2 Enhanced Host Controller" under Universal Serial Bus Controllers. If it's not there, then you may have problems. Apparently Service Pack-1 does not always correctly identify the USB controller on the 875P chipset. There are various ways to fix the problem. One solution is to delete all the USB host controllers in the Device Manager and reboot. The auto-detect function will kick in and hopefully you will see the USB2 controller in the Device Manager. Also, in the BIOS, the USB 2.0 Controller should be enabled and the Controller Mode set to HiSpeed.