|Thanks Everyone for you input. It looks like i didn't make my question clear.|
Let me try again. 8)
Assume that my system's maximum power consumption is 90W and i have two choices of power supply.
Buying a 100W power supply & a 430W power supply.
The reason i want to buy the 430W, which has the capacity far exceeds the maximum load of my system, is so that i can use it for other systems if i want to. And since the price difference isn't a lot, it makes sense to get the higher capacity for the flexibility.
However, i want to know if the higher capacity would cause more energy waste due to extra components.