What is the default voltage of your house? It doesn't change much. The question here is IF your circuit breaker can hold the house's actual energy requirements AND your pc, but it probally will.
Power Supplies usually doesn't take much of your energy, and almost all power supply coust less than 100$ per year so you don't need to worry about it. If you are buying a NEW power supply, it sure have some protection modules, so you also don't need to worry if the voltage is wrong. And it shouldn't change that much. At least if you don't turn on two showers, a tv and your pc at the same time...
Btw, sockets basically are inputs. When you plug something on it, the circuit breaker of your house will send energy to it. How much? Everything that what is plugged on the socket needs. If it is more than it can hold, then the entire house will go dark.