On
Blinking
Off
The power supply is in zero 
output mode (standby). 
When the total power 
consumption is low, only 
one of the power supplies 
delivers the entire power, 
while the other is put into 
this mode. 
Zero output advanced mode 
is on by default, and the 
standby power supply unit will 
function normally when power 
consumption increases. To 
disable zero output mode, 
choose F1 -> System 
Settings -> Power -> Zero 
Output -> Disable. 
Off On On
Faulty power supply. Replace the power supply.
On Off Off
The system is off: The 
system is connected to 
power.
1.  Reseat the power supply 
unit.
2.  Replace the power 
supply unit.
PSU should be 
ON initially when 
AC input is 
ready.
The system is on: Power 
supply not fully seated, 
faulty standard I/O book, or 
faulty power supply.
1.  Reseat the power supply 
unit.
2.  Replace the power 
supply unit.
3.  Replace the standard I/O 
book.
It usually 
indicates the 
power supply is 
not fully seated.
On Off On
Faulty power supply. Replace the power supply.
On On On
Faulty power supply. Replace the power supply.
290 ThinkSystem SR860 V2 Maintenance Manual