FWIW - I found a manual for this system and it indicates the setting should be in the advanced section of the BIOS but the setting is not present. The manual is => https://www.dell.com/support/manuals/al/en/aldhs1/alienware-aurora-r8-desktop/alienware-aurora-r8-service-manual/system-setup-options?guid=guid-71c9d160-d98d-4d22-8715-6eeffcadda64&lang=en-us

Do I need a newer/different BIOS?

Normally, if old/retro BIOS options are now missing ... it usually means the feature is Enabled (with no way to disable it).

What exact-model CPU is installed?

Using Oracle's trouble-shooting tool, what VM feature does it say is missing? What is the exact error message?

cpu is: i9-9900k on a windows 10 build version 1903 The exact Oracle VM startup error is: (VERR_NEM_MISSING_KERNEL_API). VT-x is not available (VERR_VMX_NO_VMX). Result Code: E_FAIL (0x80004005) Component: ConsoleWrap Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

Assuming you mean Oracle VirtualBox ...

Here are some tips. Looks like Hyper-V, Windows Hypervisor Platform, and maybe some other things need to be disabled.

https://superuser.com/questions/1391838/virtual-box-is-not-working-on-windows-10

They also have helpful/active forums over there. Personally, I've only used (recently) the macOS version of Oracle VirtualBox. Works fine btw. 

So just to make sure everyone is on the same page, you don't see these options in BIOs Setup > Advanced, as noted in the service manual that you quoted below::   

REPLYING TO: 

"FWIW - I found a manual for this system and it indicates the setting should be in the advanced section of the BIOS but the setting is not present."

In my prior screenshot:

Virtualization for direct I/O = VT-d

Virtualization = VT-x

I've got the exact same problem... I need to enable hw accelerated virtualization tu use VirtualBox, but there's no option for vt-x and vt-d when I go to advanced settings in the bios.

Same problem, have you found any solution? I called support, they attempted to update BIOS, and when the Virtualization options still did not show up in BIOS I was assured that it was enabled due to Virtualization showing enabled on Task Manager > Performance > CPU stats. However VT-x is not enabled according to failed VirtualBox with same error, failed Intel haxm with similar error, and the following output from Intel Processor Identification Utility:

This conflicts with the specs provided by Intel here , but according to the docs the ID Util reports supported CPU technologies, not technology functionality reported by machine, so this may actually just not be a supported feature and be a problem with Intel's documentation. Alienware support told me to contact Intel support, so that is next step unless someone here can point me towards solution.

The manual shipping with the latest R8's does illustrate the two VT lines in the BIOS. My machine (i9-9900k cpu) shipped 2 weeks ago (Oct 28, 2019) and the BIOS did contain these lines. HOWEVER, going onto Dell's Download & Driver page I saw a BIOS file (Version 1.0.7) marked "urgent". So I downloaded the file and FLASHED the BIOS. Both VT lines disappeared from the BIOS. The result is that both PCIe slots (No.1 & 4) no longer function making the installed twin NVIDIA 2080 GTX cards useless. The only video output is via the display port but I must physically remove both video cards first. I read in one of these responses that Dell was issuing advice to contact Intel support. This is not an Intel problem with the Advanced Technology Virtualization. It is a Dell Problem to correct via the correct BIOS that these machines shipped with and remove the Bogus BIOS currently on their Web site. (Ver. 1.0.7, I believe dated 2 Sept 2019). Dell needs to post the correct BIOS on their web site. I find the argument that these features are now "built in" to be Bogus. I got the same line of BS from the tech rep. This argument indicates no control over the VT technology built into the i9-9900 CPU. This issue with a bad BIOS may be traceable back to American MegaTrends who writes the BIOS. Again, in my case it's a BOGUS BIOS causing the problem. I ran the complete Diagnostic Test on the machine and everything passed.