Final answer:
The testing conducted for checking the operability of an operating system across different x86-family PC hardware is known as Portability testing. It ensures the software is compatible and functional on various computer systems.
Step-by-step explanation:
When testing a mass market operating system to ensure it runs on PCs with different configurations of the x86 processor family, the type of test being conducted is a Portability test. This testing strategy is focused on confirming the operating system's compatibility with a variety of hardware platforms, particularly different PC brands that utilize the x86-family processors. The goal is to identify defects that could impair functionality on diverse systems and ensure reliable operation across multiple hardware configurations. Portability testing plays a critical role in validating that software products can be easily transferred and used on different environments without encountering issues.