Dell PowerEdge C8000 - Manual (Page 83)

Using the System Setup Program 83
Boundaries of PSU Configuration
The number of power supplies required for PSU configuration is determined by the following formula:
X + N, where X is the required PSU and N is the redundant PSU.
PSU Number Required PSU (X) Redundant PSU (N)
4 4 0
3 1
2 2
3 2 1
2 2 0
1 1