You should be fine with either card.
Corsair is a quality manufacturer and makes great PSUs. The 670 needs 30 amps total on the 12 v rail. The 660 Ti needs less.
The least expensive 500 watt Corsair has 34 amps on the 12 v rail. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
if this is wha you have you are fine.
It depends on the total draw of the system in reality... The gpu manufacturers give PSU recommendations based on plenty of wiggle room. The newer cards are extremely efficient and the wiggle room is even greater.