It looks like I will be going 4 sensors. I ordered the new in ear and 3rd sensor but my bank decided to brake the order and send me an SMS, small buying purchase pattern my side so I can understand. Tried to log into my orders and repeat or correct the 3rd sensor order but it would not clear once back from paypal, so just ordered another sensor. now the orginal 3rd sensor is cleared off the back of the 4th sensor. Oculus appear to be telling people to only go for 3 sensors but there are also reports of 4 sensors giving 99% coverage experience (over 90%, some small brakes in experience with 3 sensors). Also have the Inateck PCI-E to USB 3.0 5-Port PCI Express Card as this is the card to get. Little cross with a vendor I bought my Asus X99 Dulux from, its USB ports failed so it was sent back for RMA,28 days later I got back an Asus X99 E, which has less usb ports on the rear I believe but what ever.