alright thank you for the help
Like boiler pointed out, those 3GB cards are for a multiple monitor set up. The extra RAM actually hurts FPS on a single monitor set up due to RAM latency. Also like he pointed out, a Rosewill psu isn't the way to go.
For a psu that will push dual 580's in SLI then these two down below are worth looking at.
Here's a quality non modular that's gotten great reviews.http://www.newegg.com/Product/Product.aspx?Item=N82E16817371050
$129.99 - $109.99 after mail-in rebate FREE SHIPPING
Antec High Current Gamer Series HCG-900 900W ATX12V v2.3 / EPS12V v2.91 SLI Certified CrossFire Certified 80 PLUS BRONZE Certified Active PFC Power Supply
This psu down below is manufactured by Enermax for LEPA and it's top of the line. http://www.newegg.com/Product/Product.aspx?Item=N82E16817194083
$179.99 - $129.99 after mail-in rebate card
LEPA G900-MA 900W SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular Active PFC Power Supply