I've been trying to install the Intel USB 3.0 eXtensible Host Controller Driver (version 3.0.0.16 as supplied by the Asus web site) but it balks when it gets to the PCI bus. At this point the entire system freezes for about 30 seconds and then a generic message is returned saying the install failed and some devices were not installed. If I try to install the PCI bus driver manually via the Device Manager (updating from the stock Microsoft driver and pointing it to the directory where the Intel USB3 drivers reside) It fails saying "The parameter is incorrect". Something has occurred in this process though, because the Device Manager is now listing the driver as Intel, version 3.0.0.16. Rebooting at this stage causes a BSOD while loading windows, requiring a repair boot and System Restore to recover.

Searching the Intel web site for the same drivers (in case the Asus copy is corrupt) only returns drivers for Series 7 or Series 8 chipsets, with no specific mention of Series 9 (I have Z97).

Why am I trying to do this? All my chipset-controlled USB3 ports (including the motherboard headers) are only operating as USB2. I have two ports fed by an ASMedia controller and they seem OK, it's just the Intel ones. this means I can't get my Akasa card reader to work, as it uses the motherboard headers.

I've tried reinstalling the chipset drivers (also downloaded from the Asus web site) to no avail. Any attempt to dislodge the Microsoft driver in favour of the Intel one results in boot failure.

The motherboard is an Asus Z97-PRO(Wi-Fi ac). I'm sorry I can't provide any more technical information at present (working nights and my PC is about seventy miles away) but if you tell me what you need I'll be back in about twelve hours...

UPDATE

I have half an answer: I went into the BIOS and changed Intel xHCI Mode to Enabled instead of Smart Auto, and all my USB devices appear to be operating correctly now. The driver still fails to fully install though, failing at the PCI bus again (although without the freeze this time). Here's a screenshot of the error message, for what it's worth.

At least now I know my motherboard is not faulty, and everything works. Partially installed drivers always worry me though, in case they cause problems further down the line...

Try to disable xHCI mode on BIOS settings.

In the following reboot (better if you have an Internet connection) check if Windows installs correct drivers.

I have discovered a fix for this!

If your issue was that you discovered your USB ports were not working, and removed/uninstalled the Intel eXtensible USB 3.0 Drivers and discovered you couldn't reinstall them - I HAVE THE SOLUTION FOR YOU!

Go to this link and install the modded eXtensible drivers.
https://www.win-raid.com/t834f25-USB-Drivers-original-and-modded.html

1) Go to the link and Scroll down to E. Intel USB 3.0/3.1 Drivers:

2) Open the spoiler and go to B. Latest modded Intel USB 3.0/3.1 drivers

3) If you have windows 8 or 10, download from the first section either the 64 or 32 bit system (based on what system you have)

4) Unpackage the zip file somewhere, open Certificate folder and then run ImportCertificate.cmd

(If you have any issues with the certificate go to this link:
https://www.win-raid.com/t1300f25-Tips-Discussion-Usage-of-quot-mod-signed-quot-Drivers.html)

5) Now run DPInst64.exe (64bit version)

6) Follow steps and restart your system.

7) Your USBs should work now!

Enjoy!