Epson Progression U12 - Manual (Page 64)

Removing the Subassembly
You need to remove the subassembly only if you are installing
or removing a hard disk drive that is mounted next to the
power supply. (See the installation instructions in Chapter 4 if
you are not sure if you need to remove the subassembly.)
Follow these steps:
1. Turn the computer so you are facing the front panel.
2. Disconnect the power supply and drive cables from the
backs of all the drives installed in your computer, as shown
below. Note which cables are connected to which drives so
you can easily reconnect them later.
power supply
drive cable
Accessing Internal Components 2-7