An AMD Athlon x4 860K and a Radeon R7 260X combination will run rings round the A10-7850K.
An Athlon x4 860K is basically the A10-7850K without the graphics, and from what I recall, also overclocks better than the A10-7850K too. You're better going with the Athlon chip and getting a dedicated graphics card.
EDIT: If you buy this quickly, you can pick up an 860K for only £42... brilliant deal!
AMD Athlon X4 860K Black Edition 3.70GHz (Socket FM2) Kaveri Quad Core Processor - Aria PC