I like the idea of selling off some of the stuff for a better CPU.
Keep the current Intel MOBO and 8GB RAM.
That's socket 1155 yeah? Should be lots of good used options, i3-i5 at 3.5GHz or so would be nice with an R9-270. You can actually get a new i3-32xx for $100.
Depending on the board you got, any sandy w/ turbo can do an extra +400MHz even without a k model...so a used i5 for ~100$ could be desirable.