RADEON HD 7770 - ASUS vs SAPPHIRE: http://www.insidehw.com/reviews/graphics-cards/7209-radeon-hd-7770-asus-vs-sapphire
Sapphire 7770 = "got packed a cooling solution of much higher quality than the usual one"
Asus 7770 = "nothing but the best of this quiet and efficient cooling solution"
Conclusion: "The cards were just too similar to avoid delving into details in search for the winner."
Also, Sapphire has the Vapor-X version which has a better cooling solution: http://www.newegg.com/Product/Product.aspx?Item=N82E16814102993
Or you can save some money and get the HD 7850 which is better: http://www.newegg.com/Product/Product.aspx?Item=N82E16814102999