We always recommend that you create an offline image of your PC once you have it configured and in a working condition. This can be by using our DBAR (Dell Backup and Recovery) software or some other media.
These guides will take you step by step through the safe removal of what are considered to be the Customer Replaceable Unit (CRU) parts of an OptiPlex 3020 Mini Tower (MT) Chassis. (CRUs are the parts of the system that shouldn't need an engineer to remove or replace.
If you are trying to change the modes on a Sunix MIO5469A PCIe RS-232 / IEEE1284 parallel port card, read the article below for information on how this card changes modes automatically rather than manually.
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