Compaq AlphaServer DS20 Service Manual page 39

Figure 1-15 shows the distribution of the power enable circuit through the system.
Opens in the circuit, or the RCM signal RCM_DC_EN_L, or a power supply detected
power fault causes interruption to the DC power applied to the system.
A failure anywhere in the circuit will result in the removal of DC power. A potential
failure is the relay used in the remote control logic to control the RCM_DC_EN_L
signal.
The cover interlock is located under the top cover between the system card cage and
the storage area. To override the interlock, place a suitable object in the interlock
switch that closes it.
System Overview 1-29