files are "Rockstar Package Files" used to store compressed game assets like textures, sounds, and models. Specifically:
If your hard drive has bad sectors, a portion of x64c.rpf may become unreadable. While Steam or Epic Games launchers will detect this during verification, sometimes the drive fails so badly that the launcher cannot overwrite the sector, forcing you to replace the file manually.
: Right-click Grand Theft Auto V in your Library > Properties > Installed Files > Verify integrity of game files .
Instead of searching for a direct "X64c.rpf Download," consider:
Specifically, is part of the core game data. The naming convention breaks down as follows: