non dell video cards require secure boot OFF in bios. Non OEM dell cards require secure boot off. This is not optional. There is no LEGACY CSM with UEFI Class 3 Bios. [URL] The truth is that it makes it more difficult to Impossible with CLASS 3 UEFI Bios to run anything other than Windows and Microsoft WHQL certified hardware.  This includes Video cards and Storage Controller cards with boot roms and tuners and anything else on ANY bus including USB. The firmware update is a certificate in the bios on the video card that is $$$Microsoft Certified aka WHQL validated with Microsoft Certificate. The OEM firmware has a certificate in the bios on the video card,driver, etc that is $$$Microsoft Certified. All future systems are 64 bit only and Win10 only. There are no more 32 bit drivers.  ATI, NVIDIA, INTEL, etc are all complying with this.  No more CSM enforces this. Any os that does not pay for certificate and write 64 bit UEFI code will not boot.  Grub/msdos  etc wont work. Secure boot "removes control from the end user and places it in the hands of Microsoft. It makes it impossible  to run anything other than 64 Windows 10 or Redhat, , Suse, Ubuntu 12.04.3 or higher". DVP9W Nvidia GeForce GTX 1050 Ti,  4GB, 75w36V90 Nvidia GeForce GTX 1060, 3GB, 120w24K8H Nvidia GeForce GTX 1050,  2GB 75w8CCF1 Nvidia GeForce GT 1030, 30w1MPR3 AMD R9-360 2GB, 75w24K8H Nvidia GTX 1050 2GB, 75w   [URL] Answer ID 3156  Published 10/25/2012 03:12 PM  Updated 10/26/2012 02:00 PM When installing an after-market graphics card into a Windows  with Secure Boot enabled, the system may not boot. Secure boot is enabled by default on WindowsPCs. When an after-market graphics card not containing UEFI-enabled firmware with DELL Certificate. (VBIOS) is installed into a motherboard with secure boot enabled in the SBIOS, the system may not boot. The majority of retail graphics cards Not DELL OEM do not contain UEFI-enabled Certificate. In order to get the PC to boot with a graphics card that does not contain a UEFI-enabled firmware the end-user must first disable the secure boot feature in the system's SBIOS before installing the graphics card. Note: Some system SBIOS's incorporate a feature called compatibility boot. These systems will detect a non-UEFI-enabled firmware VBIOS and allow the user to disable secure boot and then proceed with a compatibility boot. If the system contains a system SBIOS the supports compatibility boot, the user will need to disable secure boot when asked during boot process Instructions for manually disabling secure boot: 1) Power down the system 2) Remove the NVIDIA Add-in card 3) Boot the system using integrated graphics 4) Enter CMOS settings. CMOS settings can usually be accessed during boot, typically by pressing  F2 then F12 over and over,  (depends on the BIOS)  5) Set Secure Boot to disabled 6) If there is an option, set CSM (or compatibility or legacy mode) to enabled. 7) Save the new settings Power down the system 9) Install the NVIDIA Add-in card 10) The system should now boot  
I received a new XPS 8940 SE last week (i7-10700, RTS 2060, 1tb NVMe) and so far have found it to be very fast and quiet. I updated all drivers and  bios. As I am working, I noticed that the power button led is flashing 3 amber and 2 white lights. I ran support assist and also pre-boot troubleshooter and all came back normal. This one troubled me as in the Service Manual this sequence of flashes indicate that the motherboard needs replacing. I contacted Dell support and sure enough, they scheduled an appointment to have the motherboard replaced! The system is running flawlessly and I am using it now as my go to desktop. Quite strange and disappointing for a new Dell. I have an XPS 8700 which is still running flawlessly for 6 1/2 years! Anyone else having motherboard issues with the XPS 8940 SE?
XPS 8940 SE, new, bad motherboard