@infuscomus
Do the following to test the Win8 XHCI drivers on Win8.1:
- Create a bootable Win8.1 x86 USB flash drive using Rufus.
- Open boot.wim in 7-Zip.
- Replace the following files in folders \1\Windows\System32\Drivers and 2\Windows\System32\Drivers
ucx01000.sys, usbd.sys, usbhub3.sys and usbxhci.sys -> original, untouched from Win8.0!!! Ported drivers will crash.
- Restart and boot from it.
Worked just fine here.
If USB devices work, your issue is related to the ACPI driver.