SMPS Over Voltage Protection
The switching supply is designed to always regulate a voltage using pwm control. Ovp was designed to protect an expensive motherboard or memory board in case the pwm circuit fails, and
Leaves the output Fets in a 100% on state. This would raise +5vdc to around +8vdc or higher.

Most switchers above 25 watts have this on usually just the +5 or +3.3v logic supplies.