What key information should you provide to a customer after replacing their system board?

When replacing a system board, it's crucial to provide the customer with the 5 x 5 Digital Product Key and DPK Card. This key is essential for the activation of the operating system and other software tied to the hardware of the system. Providing the Digital Product Key helps to ensure the customer can successfully activate their system following the replacement and avoid any potential issues with licensing.

While the previous parts list, complete system diagnostic report, and warranty details are valuable information in different contexts, they do not directly impact the immediate usability and functionality of the replaced system board. The Digital Product Key specifically facilitates a smooth transition after hardware replacement, making it the most pertinent information to provide to the customer in this scenario.