DrHerbst :
clutchc :
It will run. But you may get lower performance or shutdowns if the PSU gets overloaded. Mostly it depends on WHICH 500W PSU you have.
As mentioned above be quiet 500w (gold 80+)
Most be guiets are pretty sound. If it is one of the gold models, it should be able to provide the necessary power even under above max load.
Is it this one? http://www.bequiet.com/en/powersupply/527