One of the key responsibilities of an Architecture Board within the context of TOGAF is to achieve consistency between sub-architectures. This board is typically responsible for overseeing the development and maintenance of the enterprise architecture, ensuring that it aligns with the organization's overall strategy and objectives. They play a critical role in ensuring that all sub-architectures (like Business Architecture, Data Architecture, Application Architecture, and Technology Architecture) work together cohesively and support the overall enterprise architecture vision and strategy.