Same problem here, got the adapter 2 days ago for the VIVE.
ASUS PRIME B250-PLUS
I5-7400
GTX 1080
8 Go DDR4
Use to worked great while wired, huges lag and poor graphics using Wireless Adapter. I tried various PCIe slots, same everytime. Also tried the BIOS Uptade, and forcing PCIe slots in Gen3.
If changing the motherboard is the answer, i'm not ready to put another 300€ in it!