# vSync for gameplay in monitor and VR headset in Unity not being consistent?

Following my previous question, I'm building a project, my monitor refresh rate is 60Hz, and in my project I have set my vSync value into 2 so I can get 30fps.

QualitySettings.vSyncCount = 2


It worked perfectly, I built my project and I got stable 30fps. But after I plugged my VR headset (HTC Vive) to play the same project, my framerate drops and only reach around 10fps. Why is this happening ? FYI, Vive's refresh rate is 90Hz. In this case, will vSync adjust itself to my monitor or Vive's refresh rate ?