Several years ago, the appearance on sale of fake processors was common. Usually we deal just with low-end models packed in boxes of more expensive processor. Intel and AMD actively develop more secure design packages.
Cases of counterfeit in video cards are more rare, but theoretically nothing prevents an attacker to put a younger model in a box from older. NVIDIA has distributed among its partners a warning of the existence of fake graphics cards GeForce. In this regard, NVIDIA calls video cards partners to purchase only from authorized vendors.