Building gaming PC- will I be able to run Dolphin well?

[leolam]

Yes, an i5 6500 and a R9 380 should be pretty powerful and should handle Dolphin easily. However, I recommend getting an unlocked (K series) CPU (as well as a motherboard which can overclock) if it's not too much more expensive -- it will certainly be useful if you ever get CPU bound and need some speedup.