I would like to know if the mother card brings a serial or something with which the current one can be identified and be aware if a technical evil has changed it?

When you take the computer to the PC technician, you have to be a user who knows what you have. If your PC is of the Desck Top type, you have to do a preliminary balance, Identify the MAIN motherboard. (I mean you have to look for the license plate) You have to know what micro you have, how much RAM you have; Source; Rigid disk capacity ... Unfortunately, when a dishonest "technician" sees a vulnerable client, he usually takes advantage of the client's [i] ignorance [/], (it usually happens a lot unfortunately with the elderly) I unfortunately repaired PCs that were stolen components, simply by seeing the purchase receipt, many people keep the papers. This "staff" unfortunately leave technicians like me, who do not have a large scale ... We mostly have software dramas ... (Reinstall Windows is the most usual) The electronics are more solid normally, well no thus the hard disk, which is more delicate. If the PC is dead, run with disadvantages, but if the PC was walking, but does not accept the budget, it is the technician's obligation to show that the PC is as it was brought ... Ask for references, to people who have taken the computer to someone time...