Graphic Card Power ?

Just purchased from newegg EVGA 512-P3-N871-AR GeForce 9800 GTX+ 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready. I have been told that my power supply was strong enough to run but having doubts. My power supply is XION XON-500F8X2-201 500W ATX Ver2.2 SLI Ready Power Supply. I am getting conflicting answers as if this will be enough to run this card some say yes some say no. Now from the reviews this card is a 738 mhz core its seems to be mislabled. My other dilema is this my case is a mid tower atx it only has one 8o mm fan and Im concernd this case is not going to allow this card to cool properly. So my question does any one have one of these cards if so can my psu handle it? Am I going to have to get a new case I was told I would have to get anohter case that has fan up top and back to create a cooler air flow. Im really hoping that I can use this case and not buy another on a budget no money. Any thoughts? Thanks