Please enter the service tag number ( or use Detect Pc) onto the link below. After, stroll down to the IR Camera Driver and expand it. You could now download and install the IR camera driver onto the system.

Support | Dell US

Note: You could select the Detect Drivers in your Dell Product Support page to search for IR camera driver and other much needed drivers and firmware for the system.

The IR Camera driver for the Alienware 17 R4 is only if that model has a Realtek camera (on top of screen you will see 2 cameras). If your Alienware 17 R4 has the IR camera built into the Tobii device, there is no fix for it. Tobii is working one but still needs support from Dell and Microsoft to "fix". This is due to Microsoft pushing out an update back in the Fall of 2017 with the Windows 10 Fall Creators Update. This needs to be addressed by Dell as they still advertise these laptops with Windows Hello compatible. If you do have the 17 R4 with the IR camera on the Tobii device, contact, Tobii, Dell and Microsoft.

https://answers.microsoft.com/en-us/windows/forum/windows_10-hello/windows-hello-alienware-17-r4/51b318e4-54be-4a59-b07b-013fe338a491

https://help.tobii.com/hc/en-us/articles/115003032934-Windows-Hello-not-functional-after-Fall-Creators-Update

Thanks for sharing the information Deltam2. :BigSmile:

I just reloaded my Alienware last week and noticed my HELLO was no longer working. Guess this explains it.
Thanks for the info. 
I'm not totally sad about it, doesn't take much to punch a four digit code in to login, just like the convenience of it. 

There is a fix. Released this month. I have one camera with the Tobii tracker at the bottom.

Tobii just released an update driver so that windows hello will work in March 2018. Unfortunately Dell has not pushed or even received the update. Go to their site and compare your aleinware 17R4 will the pictures like for instance i have a camera at the top and the Tobii eye tracking at the bottom of my screen. Now finally Hello works.