is having a big psu (watts) a disadvantage?

[skyra]

seasonic s12 energy plus 650W
gigabyte ga-p35-ds3r rev2
intel core 2 duo e6750
western digital sata 250gb hdd
g.skill 2gb ddr2 4-4-3-5
evga 8800gt superclocked

using a usb keyboard, mouse, printer if that matters..

I think 650w overkill? Are there any disadvantages to having too big of a PSU =(

Would this psu last me longer than say a 400W or 500W PSU?

[Paul_Johnson]

The only disadvantage is you are going to probably be below the units peak efficiency most of the time which peaks around 50% of its capacity.

[andyOCZ]

You will only use the wattage that your system requires, so there is no real disadvantage having a larger PSU. Some might argue that you may not have the same efficiency as a smaller unit, but that's really splitting hairs.

I always recommend getting a PSU with some wattage headroom. You will put less strain on it, and you may put off having to purchase a new PSU when you decide to upgrade parts.