The DirectX error in NFS Payback typically occurs when the game's graphics requirements exceed the capabilities of your system's graphics processing unit (GPU) or when there's a compatibility issue with the DirectX version installed on your system. However, with only 512 MB of RAM, the issue might also stem from insufficient system memory.

Before fixing the error, you need to understand why it occurs. The error is about your actual VRAM. It is caused by a detection bug in the Frostbite Engine (the engine NFS Payback runs on). The game asks DirectX for a report on your GPU memory, but due to:

Under graphics profiles, ensure it is set to use the high-performance discrete GPU. 3. Perform a Clean GPU Driver Installation

By following these recommendations and solutions, you should be able to overcome the DirectX error and enjoy a more enjoyable gaming experience with NFS Payback.