Usually if a product key is requested the wrong Edition of recovery media has been sent out. The Windows 8.1 Home and Windows 8.1 Home Single Language Editions commonly get mixed up. You are best to make your own bootable USB. Either Windows 8.1 or Windows 10 TH2 (which will accept your Windows 8.1 OEM key). See here for details:

http://dellwindowsreinstallationguide.com/download-windows-10-oem-and-retail-iso/

http://dellwindowsreinstallationguide.com/download-windows-8-1-retail-and-oem-iso/

thanks for responding--- i no longer have a MS OS on my machine--- i dont think the media creator  will work with a non MS OS

Okay so you will need to install Windows 10 TH2 using the Techbench .isos. Follow this guide which instructs in downloading the .isos via the direct links and making the bootable USB using Linux:

http://dellwindowsreinstallationguide.com/download-windows-10-th2-and-prepare-a-bootable-usb-on-linux/

Try with the Windows 10 TH2 .iso first, if you are requested to input a product key select cancel and then try again with the Windows 10 TH2 Single Language .iso.

Thankyou--i will give it a shot

alright--- i made a bootable  usb stick with win 10 th2 -- i actually got windows 10 to install-- i then ran rweverything and another program that was supposed to read the product key off the bios---i have determined there is no product key embedded in the bios/uefi according to these two applications-- it makes sense considering the win 8 OS recovery disk i bought from dell will not install without a product key . ive screwed around with this for 4 days and hours on the phone with dell. i think i am going to be done with Dell and Microsoft for good. it could have been so easy for them to put a label with the product key on the machine . MS has gotten ridiculously complicated with their product key insanity. you can tell its insane by the amount of people on the net finding it impossible to reinstall an OS if their drive croaks.there are either no product keys supplied or embedded keys that cant be  accessed - i have to say that the dell tech people i have been  on the phone with should be flipping burgers- i just cant seem to make them understand that the disk they sent requires a product key to install-- they just dont seem to  grasp that  .  (sorry , i didnt mean to insult people that flip burgers)

Okay so the fact that RWEverything finds no MSDM table means you have no product key in the UEFI BIOS. This means no Windows 8.1/10 installation media will work. I have seen a handful of cases where the key has been lost like in your case but overall it is extremely rare i.e. you are unlucky. In one of the cases updating the UEFI BIOS to the latest revision helped (this didn't work in any of the other cases but its worth a try).

Please press [Windows] and [ r ] type in msinfo32 and let me know the UEFI BIOS revision. Check also that its showing XPS 8500 as the model and Dell as the manufacturer respectively. If it is not A12 then update it. See here for more details:

http://dellwindowsreinstallationguide.com/updating-the-bios/

http://downloads.dell.com/published/pages/xps-8500.html

After you have updated (if you updated) check RWEverything again for a MSDM table.

Strictly speaking if you still have no MSDM table the official solution is that you will have to get Dell Technical Support to replace the motherboard on your system because the key is now considered hardware and not software... This however may prove difficult as the hardware diagnostics for the PC are likely to pass and Dell may be reluctant to replace the motherboard/system.

Personally I would however advise taking the unofficial Windows 10130 Upgrade path to make your system a Windows 10 Pro Device:

http://dellwindowsreinstallationguide.com/windows-xpvista-%e2%86%92-windows-10-free-upgrade/

In your case ignore the steps to check system requirements (you already have Windows 10 running so you know it works and this system is very powerful), Also when making the USBs ensure you use the GPT partition scheme for UEFI BIOS and have the USB FAT32 formatted. Ensure SecureBoot is enabled in your UEFI BIOS setup.

thankyou for responding--- i have already taken windows 10 off of my machine- so i will not be able to update the bios at this point-- i will investigate how i can update the bios through linux if possible--- it would be a lot easier for me to locate a win7 or win 8 with a product key than fooling with this losing  proposition any longer--- i have no desire to ever use win 10-my main reason for wanting windows at all is so i can run  an adobe program and an astronomy program that wont run on linux . my intentions were to  dual boot on separate drives with "easybcd--- i would use the windows for those purposes only and linux for everything else--- linux wine isnt an option because its still not ready for prime time--- and i dont have anything i can load legally into a VM-- but thanks for your time--- spending $100 for a version with a valid product key is probably the way to go