The best gpu for scrypt mining is the Asus strix r7 370 4gb. This bad boy is power efficient. It draws 110w and gives you 15mh (17mh OC) of ethereum mining. Right now you can get them with a $30rebate brand new. https://www.amazon.com/Radeon-Overclocked-256-bit-DisplayPort-Graphics/dp/B00ZQ3QVJK/ref=as_li_ss_tl?ie=UTF8&qid=1471500653&sr=8-1&keywords=asus+strix+4gb&linkCode=ll1&tag=technology304304-20&linkId=15ea6672c1c998b748dfe71d0d8ab041

I have 5 of these gpu´s in my rig. To power my rig I chose Evga 1000w Gold with 6 pcie vga cables.

Very important to get a real good power supply.

It is better to use the RX 470 to mine the Ethereum. The price is lower than the 480 and has similar mining performance.

I heard that Eliovp has modified the RX 480 BIOS and can mine the Ethereum at over 31 MH/s. But he has not made one for 470 yet.

Some people has made some BIOS mod for the 470. It seems the 470 can achieve similar results as the 480.

there are modes for the 480x also which will give you more hashes if care fully done. the price difference matters after an extend!!!

yea also you can mod it, there is a video on youtube of one guy who gets 29mh/s on his R470

He must have a very good RX 470 with good quality memory. Not many 470 can reach that even after mod.