Hi Devin,
Please advise how do you set the resolution to 640x480? What section in nuitrack.config do you edit? What is your sensor?
You can find the instructions on how to set a different resolution on different sensors in our knowledge base.
See the questions “How can I change Depth/RGB resolution for Orbbec Astra Pro / Persee?” and “How can I change Depth/RGB resolution for ASUS Xtion2 / Orbbec Astra?”