Locked frame rate in pcvr games

That's a PC/GPU problem, not a headset or Link issue.

This isn't necessarily a setting that always gets respected. Your actual framerate is going to depend on your graphics card capabilities, what else is running on your PC (and consuming graphics resources), as well as the game itself and the scene being rendered and how well the game developer optimized their scene rendering performance.

Overall, reducing your monitor refresh rate will help. redrawing the monitor frame at 144hz gets pretty expensive. You can also try to reduce the size of your render viewport on your host PC. Another think to consider is your GPU hardware and what other applications are concurrently running on your host PC. Another thing to check is your link cable (and cable quality) -- sometimes signal interference can affect framerates.

Usually when a frame cannot be rendered in the target timeframe, the render refresh rate gets lowered (and changes dynamically). Some VR hardware will detect that a scene wasn't rendered in time and they'll go into reprojection mode to render the previous frame twice -- ie, you render at 90fps, but in reprojection you render at 45fps. In some games and in some scenes, you may notice periodic framerate drops as a function of scene complexity. Usually the common culprits are quad overdraw caused by masked or translucent textures, lighting and shadows, material shaders using pixel offset mapping (POM), groom hair, too much material complexity, reflections, ray tracing, etc. Usually the solution is to make sure your hardware is at or above min spec as recommended by the game developer, or pester the game developers to optimize their scenes better for VR performance.