are you overclocking your system?
if no, its ok to use dynamo, ive been using one for 2 years na. buy one which has a way higher capacity of what you would normally need, its still way cheaper by all acounts. and if it breaks after 2 years or so, hey buy another one, its still cheap. im only being practical here, no offence to others.
if yes, better get a higly stable psu.
btw if you see voltages fluctuating a lot in high numbers considering the psu is brandnew then the voltage control ic of the unit is defective, have it replaced, also check your outlets there are cases where theres nothing wrong with the psu but the outlets themselves are very degraded.