Getting a 4690k is there anything I should know about this CPU? What would I expect to OC to? Quirks?
4.6 - 4.8ghz should be easy, anything more will probably need way more voltage then usual. Otherwise there is nothing special, what mobo are you getting?
For your 290x, you should see some more performance. I upgraded from i5-760 @ 4.2 GHZ to this cpu and my GPU performance definitely increased a bit as well as cpu of course. You'll probably get more if you had CFX.