If your house pwr OK, I'd suspect PC's pwr supply
Where I live it's rare to have low voltage. We have thunderstorms, but when we have power (which is the vast majority of time), it's pretty constant at around 118 volts. If yours turns to be similar, then I'd suspect the power supply in your computer. As Bob reminds us often, power supplies lose a lot of their punch over time, especially if they've been subjected to some harsh conditions.