Asus T3-PH1 - Manual (Page 20)

2-4 Chapter 2: Basic installation
2.4 Removing the power supply unit
You need to remove the power supply unit (PSU) before you can install a
central processing unit (CPU) and other system components.
To remove the PSU:
When removing the PSU, make sure to hold or support it firmly. The unit
may accidentally drop and damage other system components.
1. Lay the system chassis on
its side on a flat and stable
surface.
2. Disconnect the optical drive
power connector.
3. Locate and remove the two
screws that secures the PSU
to the chassis.
4. Lift the PSU in the direction of
the arrow to a 90º angle.