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BugZero found this defect 674 days ago.
OptiPlex 7000 may have a COM port device entry in Device Manager even through the computer was not purchased with the optional add-on COM port. This entry may not be removable in Device Manager as there is no option to disable it in BIOS as per the service manual. Affected Models: OptiPlex 7000
This is working as designed, and the operating system is detecting the COM port on the motherboard. The BIOS does not show any option to disable the COM port if an add-on port is not fitted to the computer.
Purchasing the computer with an add-on COM port or adding one after point of sale provides BIOS options to disable it or change the serial port address.