XPS 8930, upgrade existing SSD

You don't have to buy the new SSD from Dell. You will find more choices and better prices elsewhere.  Crucial.com has SSDs compatible with XPS 8930 here. Samsung and Western Digital, etc also have compatible SSDs.

Some SSDs brands and their software (Crucial, Samsung) don't work well when BIOS is set to RAID, which is how Dell configures the XPS 8930. So you should probably change that setting before installing a new SSD. This has to be done the right way or the PC won't boot:

1. Open Cmd prompt  window, Run as administrator.
2. Copy-paste this command, which will start Windows in Safe Mode the next time you reboot: bcdedit /set {current} safeboot minimal and press Enter
3. Restart the computer and enter BIOS setup by tapping F2 when you see the Dell screen
4. Change the SATA operation mode from RAID to AHCI
5. Save the change and exit Setup. Windows will automatically boot in Safe Mode
6. Open Cmd again, as in step #1
7. Copy-paste this command, which will start Windows in Normal Mode the next time you reboot: bcdedit /deletevalue {current} safeboot and press Enter
8. Reboot and Windows will automatically start with AHCI drivers enabled
9. Confirm that everything works properly (Windows, apps, etc)

Now you're ready to image the current SSD.  You need imaging software, such as Macrium Reflect (free for 30 days), Acronis, etc. 

Create an image of all partitions on the existing SSD, and save the image on an external USB HDD.  The imaging software should also offer an option to create a bootable USB stick that you'll need so be sure to create one.

Once you have the image saved and a bootable USB, swap in the new SSD (check XPS 8930 Service Manual for details), and put the old one somewhere safe as a backup.

With XPS 8930 powered off, plug in the bootable USB stick and the external USB drive with the image. Power on. and tap F12. When the menu opens, select option for to boot from the USB stick.

When the imaging software loads, copy all partitions in the image onto the new SSD, copying the C: image last. Depending on the software you use, there should be an option to expand the C: partition to use all the free space on the new SSD, but only the last one copied onto the SSD can be expanded. So make sure you know how to expand C: before you start or all the extra space on the new SSD will be wasted.

When the image is copied and C: expanded, exit the imaging software and reboot Windows normally. It should boot directly from the new SSD.