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[genericname]

Does installing a high watt power supply effect my PC? Will it give my parts more power than they need?

[Eigenvektor]

Power supplies "make available", they don't "push". So a 1000w power supply is able to provide up to 1000w, but your components will only draw as much power as they need.

 

Every power supply has an efficiency rating (or more precisely a curve) that tells you how efficient that power supply is at a given load. An oversized power supply that e.g. is only at 20% load may be less efficient than a smaller power supply that is at e.g. 60% load. So the larger power supply could end up drawing more power from the wall than the smaller power supply to generate the same amount of power.

[kaixax555]

No, it will not give more power to the components than they need. The parts in the PC "pull" the power from the power supply, not the power supply "pushing" the power to the components. Buying a bigger power supply means you have more headroom so that in case the parts need to "pull" more power, there is spare power available to pull.

Think of the power supply as a warehouse with a fixed amount of storage and fixed rate of input. Shops pull as much products as they need from the warehouse, the remaining is stored in the warehouse as excess inventory. Having a bigger warehouse means shops can pull more products without running out of stock. If your warehouse is too small, shops can't keep enough products in their shelves because the warehouse is empty and cannot supply any more.

This is why most people recommend to buy power supply with enough headroom for your needs.