Make Rufus show internal hard drives

Solution 1:

Rufus dev here. If you REALLY want to try to play with internal drives, there is a non-publicized cheat mode (Ctrl-Alt-F -- be mindful that this is not the same as Alt-F) that may list internal drives, such as SATA and so on, provided they have been set as REMOVABLE by your BIOS or UEFI firmware. For instance, this cheat mode should let Rufus list properly configured eSATA drives, that you may have plugged into your motherboard.

Of course, if you use this UNSUPPORTED cheat mode, you are 100% on your own.

Solution 2:

Actually, Rufus developers don't have a plan to support Internal Hard Drives. do you plan to support internal HDDs SSDs?.
To install windows from internal HD you can use:
Yumi Multiboot UEFI if you have (Secret boot / GPT disk / UEFI).
or Universal USB Installer if you have an MBR hard disk.