I'm building 2 rigs i bought 6 rx 470's for my first rig should i buy r9 390's for my second rig ? Less used r9 390 second hands with warranty cost like 255-265 dollar in here(these cards used 2 month without oc) and rx 470's cost me 235 dollar. Any tips ?
If your electricity cost is more than 0.15 to 0.2 dollar/kWh, it is better to buy the RX 470 or 480. Otherwise, buy the 390.
My electricity cost nearly 0.12 dollar/kWh Thanks for tips mate

Does the RX 480 4gb have much of a difference than the 8gb version?
There is a 15 mhz diffrence atm but in the future it will make more diffrence i guess.