Hi,
I have a Dell Optiplex GX270 SFF which had a defective PSU (HP-L161NF3P) fan.
After replacing the fan and testing the unit it now boots only after a few tries.
The voltages are all in range.
Capacitors have correct capacitance and are visibly not blown but I do not have an ESR meter.
Powergood signal is present after 350ms (measured with HDD as load).
I have tested the system with a larger PSU from another Dell (not SFF) and the computer works well, so I guess the PSU got a damage from the fan defect.
The voltages at the motherboard are correct...