There could be several reasons why some new motherboards may be faulty upon purchase. Here are a few possibilities:
1. Manufacturing defects: Despite quality control measures, there is always a chance of some defective units slipping through the manufacturing process. Complex electronic components like motherboards are subject to a range of potential issues during production, such as faulty soldering, damaged components, or improper assembly.
2. Transportation and handling: During shipping and handling, motherboards can be subjected to rough treatment or physical stress, which may result in damage to delicate components or connectors. Even a small amount of force or impact can cause issues that might not be immediately apparent.
3. Compatibility issues: Motherboards need to be compatible with various other hardware components, such as processors, RAM modules, and graphics cards. In some cases, a compatibility issue between the motherboard and other components could lead to system instability or failure.
4. Power-related problems: Power supply issues can affect motherboard functionality. Inadequate power delivery, voltage fluctuations, or inconsistent power can cause a motherboard to malfunction or fail to power on.
5. User error: Sometimes, faulty operation during installation or configuration can lead to apparent motherboard issues. Mishandling components, improper installation of CPU, RAM, or expansion cards, or incorrect BIOS settings can result in a non-functional system.