To fully leverage a new 64-bit processor upgrade, which other component will likely also need to be upgraded?

Upgrading to a new 64-bit processor requires the operating system to be compatible with the architecture to take full advantage of its capabilities. A 64-bit processor can handle more memory than a 32-bit processor and is optimized for better performance when running 64-bit applications. However, if the operating system is still a 32-bit version, it will not be able to utilize the enhancements offered by the newer hardware, as it would limit the system's memory addressability and the ability to run 64-bit applications.

In contrast, while other components like RAM and the motherboard may also need to be updated to support the 64-bit processor, especially if they are older or not compatible, the prime requirement for leveraging the full capabilities of the new processor is indeed the operating system. If the OS remains in 32-bit, the upgrade's benefits cannot be fully realized, making the operating system the correct focus for this transition.