Epson Progression U12 - Manual (Page 119)

Before you install a hard disk drive in the internal drive bay,
read the following guidelines:
The internal drive bay can accommodate only half- or
full-height hard disk drives that are 3 inches wide. If you
are installing your first half-height hard disk drive, install it
in the position farthest from the power supply.
If you want to install a full-height hard disk drive, you first
need to remove any half-height drive installed in the
internal drive bay. See “Removing a Hard Disk Drive From
the Internal Bay” on page 4-25.
If you are installing or removing a hard disk drive in the
position next to the power supply, first remove the
subassembly as described in Chapter 2.
internal drive bay
4-16 Installing
and Removing Drives