Well, on the newegg.com website under the details for the 5870, it says it need 900w for 2 of these cards in dual mode under the system requirements. This is an eyefinity 6 so I'm not sure if that is different from the normal 5870 as well. I only have a 750w power supply so that is why I am wondering before I buy another one. Thanks.
Here is the link;http://www.newegg.com/Product/Product.aspx?Item=N82E16814102888
P.S. Sorry about the bump, wont do it again, will just edit.