Dell OpriPlex XE3 Service Manual page 61

d expansion card
e M.2 PCle SSD
f SD card reader
g memory module
5 Disconnect the following cables from the system board:
a PSU [1]
b power cable and SATA cable [2]
c speaker [3]
d PSU [4]
e power distribution for optical drive and hard drive [5]
6 To remove the system board:
a Remove the screws (8) that secure the system board to the computer chassis.
Disassembly and reassembly 61