I know how it can be annoying and how it can make one distressed to the point of replacing the internal reader with an external one which can be plugged off.
It can be a nuisance, especially at night.
The BIOS does not have any specific item to switch off power to USB ports.
In order to make the annoying LED switch off, please set these items (according to
the manual, section 2-7: "Power Management Setup"):
set this to "Enable":
set these to "Disable", if needed:
- USB Wake Up from S3
- Modem Ring Resume
- PME Event Wake Up
- Power On By Mouse
- Power On By Keyboard
- Power-On by Alarm
Note that it may be unnecessary to disable the last 3 items.