If your Rift is working at all, it is definitely using the GTX 1660Ti. No Oculus headset will run on integrated graphics.
If integrated graphics was enough to run a Rift, facebook would have got their 1 billion users without having to invent the Quest.
i5 6600k - GTX1060 - 8GB RAM - Rift CV1 + 3 Senors - 0 PROBLEMS 1 minor problem
Dear Oculus, "If it ain't broke, don't fix it", please.