Pick whichever one is cheaper, doubt there's much difference. The Asus DirectCU cooling should be better, you need to decide if you want to spend the extra money for it.
http://www.anandtech.com/show/5541/amd-radeon-hd-7750-radeon-hd-7770-ghz-edition-review/23 : Total power consumption with a 7770 + Sandybridge-E proc touches 250W at max. You can check GPUReview for power draw of a GPU; your 7770 power draw is rated at
80W. Throw in another 90W for the i5 CPU and a generous 100W for the rest of the system - HDDs, Fans, Motherboard, and thats 270W at most. A 430W should easily be able to handle it.