Tracking Judder - FIXED

[Icing]

EDIT: Fixed by swapping the the USB connection of the HMD Link Box from USB 3.0 to 2.0 on my motherboard. I guess my motherboard's (Gigabyte GA-Z68AP-D3) USB 3.0 implementation is lacking. Here's where I found the solution https://www.reddit.com/r/Vive/comments/4g7ym6/htc_vive_tracking_wobble_jittering_thread/d2wllqj

My Vive tracking has constant judder. View video fullscreen to more easily spot the issue.
https://www.youtube.com/watch?v=LHgtdEj8WhE
Interestingly, tracking is very smooth when shielding the headset from the 2nd base station, so I think there's some mismatch going on between base stations.
I've spent the last two days trying to troubleshoot this, and I'm out of ideas. Wondering if my unit is bad.

System Specs:
GTX 970
i7-3770k
Windows 7

Here is a video showing base station setup and play area.
https://www.youtube.com/watch?v=SR2FmxMY0cI

My troubleshooting steps so far:

• Eliminated all reflective surfaces in my room
  
• Covered windows (also tested at night with no sunlight)
  
• Updated all firmware
  
• Tested with both vanilla and beta SteamVR
  
• Arranged base stations at opposite corners of the room and side-by-side
  
• Mounted to wall and set on tables (was suspicious walls were vibrating).
  
• Tried with and without sync cable
  
• Tried with wifi router unplugged

All scenarios produce the same judder.