If you are a DIYer and create a miner, no certification is needed. You need to follow good practices and you will be liable if there is any electromagnetic interference.
However, if you manufacturer and sell a product, in this case a class B digital device under FCC part 15, you are required to follow best practices and certify that the product meets FCC part 15 specifications and the following statement must be in a conspicuous place on the device:
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
The following must also be in the user manual:
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna. Increase the separation between the equipment and receiver. Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. Consult the dealer or an experienced radio/TV technician for help
Ultimately though it seems that it is the responsibility of the user to keep emissions down. If there is an issue, even if the product does not have a part 15 certification, it the users problem.
Though the FCC may still come a knockin' at the manufacturers door. As long as a neighbor doesn't complain (highly unlikely), I don't think there will be a problem.
This is my understanding for now. If I am shown I am wrong, then it will change.