There is no "on average"... Either it will or it won't..
Since that card pulls all it's power from the mobo, the power requirements of the card is less than 30 watts, which means that any 350 watt PSU can run that card easily as long as you don't have 6+ hard drives or something that you need to power in addition to the card..
Onboard RAID vs. 3Ware RAIDI never recommend people run RAID-5 with onboard chipsets.