NightStrike wrote:
What motherboard do you have? It's always possible that there is a
riser pinout for a serial port somewhere in the front of the board for
connection to a front panel mount.
No, I checked for that. Besides, this port would appear in Windows' device manager even if it wasn't brought out of the board. I also explored the possibility of a serial port used internally to connect to some type of monitoring chip, but nothing there either. The board is a fairly old micro-ATX with fairly limited connectivity (hence the USB-to-serial cable).
Nefastor