Does the noise go away when you un plug the wifi adapter?
I was noticing a low volume tapping noise with my carpc on. Mostly when sitting in my driveway. It was driving me nuts until I noticed that the light on my Wi-Fi adapter was blinking in sync with it. I tried fixing it by plugging the audio adapter directly in to the PC vs. the hub where the adapter is, but the noise is still there.
Anyone have any ideas other than buying a new Wi-Fi adapter?
IF your wifi adapter has provisions for an external antenna, move the antenna outside of the vehicle. The sheetmetal will act as a shield.
If that's not an option, move the wifi adapter as far away from audio cables as possible.