A black wire...there are many black wires coming out of a
PSU. It is one thing to cut the wire and another to leave
it unconnected with the header block with name still present.
If it is not a 4-conductor wire, then it being snipped might
have no or minor consequence, e.g., PSU fan tachometer lead.
Next, what OS? If there is a major change in hardware, some
OS's (e.g., Windows NT, 2000, XP, etc.) do not adapt well to
the hardware change. Depending on which OS, a re-install may
be in order and this could be the cause of the errors.
HTH & GL.