I had to do the same thing when updating from Windows 7 to Windows 10, but recently the April 2018 Windows 10 update broke my Alienware laptop drivers again.  I thought I would share the solution to get your Alienware m17xR3 Audio to work with Windows 10.  Here are the steps:

Probably at this point Windows 10 tried to update and reverted back or failed altogether.  You will get a solid white or black screen when Windows 10 tries to start up then it's game over.

Restart laptop and enter BIOS, F2 at Alien Logo

Disable High Definition Audio

Install/Upgrade Windows 10

Install video driver for your particular laptop graphics

Download R289922

Download R298411

Right-click Start Menu, choose Device Manager

Disable Video Driver under Display Adapters (It will now have a "down arrow" icon on the driver)

Restart

F2 to enter BIOS

Enable High Definition Audio

Install R298411 IDT Audio Driver

Open R289922 install to extract files, but do not install, Cancel!

Go to C:\dell\drivers\V05PT\OEM\Dell

Copy IDTNGUI.startup to C:\Program Files\IDT\OEM

Go to C:\Program Files\IDT\WDM

Run IDTNGUI.exe

Advanced

Enable Power Management... done

Go back to Device Manager and Enable Display Adapter

Restart one last time

If sound appears to not be working...

Right-click Speaker Icon Tray, choose Sound

Playback tab

Click Speakers, Set Default

Happy Windows 10 Computing!