How to Install OpenIndiana

1. Update the PC's BIOS to the latest version. Dell instructions are here
2. Download the OpenIndiana Live USB image
3. Ensure the USB flash drive to be used is properly formatted by creating a new partition table corresponding to the OS you'll write the installation image from on the flash drive. Do this in GParted (manual) . Write from Linux or BSD only
4. Write the OpenIndiana Live USB to disk using: dd if=OpenIndianaLiveUSBFile of=/dev/USBDiskIdentifier status=progress
5. Enter the PC's BIOS
6. Set boot mode to UEFI
7. Exit PC's BIOS. This should cause the PC to automatically restart. If it doesn't, manually restart it
8. Press the required boot menu hotkey when the OEM logo appears onscreen. This hotkey is F12 for the Dell OptiPlex 390 MT
9. Select the USB entry under the UEFI heading. This entry might also have an alphanumeric code
10. Hit Enter
11. When the OpenIndiana boot menu appears, hit 5. All the options are explained here
12. In the following menu, set ACPI and Verbose to On
13. Hit 1 to return to the previous menu
14. Hit 6 to ChainLoad diskn, where n is a whole number. This should cause the graphical live environment to boot
15. When the live enviroment boots, double-click the Install OpenIndiana desktop shortcut
16. When the installation is complete, reboot as suggested, while pressing the PC OEM's BIOS hotkey. This hotkey is F2 for the Dell OptiPlex 390 MT
17. Set the boot mode back to Legacy
18. In the Legacy boot mode list, move the disk to which OpenIndiana is installed to the top
19. Save your changes and exit the BIOS. The new OpenIndiana installation should now boot just fine