Advantech PPC-57 Series Manual page 26

You need only remove the rear panel to replace the DRAM, power
supply, I/O adapter, and certain other components. To remove the
rear panel, first verify that all power sources to the PPC-57 have
been disconnected. Then remove the six screws on the rear panel
and pull it away from the PPC-57.
PPC-57 User's Manual
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