ATX12VO (12V Only) Desktop Power Supply
Design Guide
Overshoot at Turn-On / Turn-Off (Required)
The output voltage overshoot upon the application or removal of the input voltage, or the assertion/de-assertion of PS_ON#, under the conditions specified in Table 4-2, shall be less than 10% above the nominal voltage. No voltage of opposite polarity shall be present on any output during turn-on or turn-off.