Simple answer is yes....theoretically! However if you have a decent quality PSU then it has its own protection mechanisms:
OCP (Over Current Protection)
OVP (Over Voltage Protection)
OPP (Over Power Protection): overload protection, sometimes called OLP
OTP (Over Temperature Protection)
UVP (Under Voltage Protection)
SCP (Short Circuit Protection)
Then any mains grid power issues should not impact your PC components...they might make your PSU go bang however. Obviously if you have a cheap generic PSU, it may well have very few (if any) of the above features in which case your PC is at risk.