AMD's new Kaveri APU is very interesting piece of hardware. It's the first processor to work according to the HSA principle, which means that the CPU and GPU work together as equals in an efficient manner. The downside of new technology is that very little compatible software currently exists, at least not mainstream software.The performance gain is therefore largely a theoretical one, so let's hope for AMD that enough software developers are willing to include HSA support in the future.
If we look at the software that is available today, the strong point of AMD's new APU is its graphics card. Steamroller CPU cores may be faster than the Piledriver cores, but their lower clock frequency largely undo that performance gain.
The new integrated GPU uses Graphics Core Next architecture from the Radeon HD 7000 series and the new AMD R7 and R9 cards and is even related to the GPUs inside the Xbox One and Playstation 4. That will surely prove to be an advantage, especially considering Mantle. AMD was already ahead of Intel in this department, and now extends that lead. The actual performance difference between the new A10-7850K and the A10-6800K isn't as big as we expected. We can't entirely go along with AMD's claim that you can play virtually all modern games in Full HD resolution, but it's close. However, if you want to game with a separate graphics card, you should definitely choose the new AMD chip over an Intel processor.
The extras are impressive as well. It's great that AMD further refined its UVD technology. The promise of an HSA-compatible HEVC decoder and full 4K support make the Kaveri chip a perfect solution for HTPCs. There's also TrueAudio support, but we have to wait until games such as Thief to find out what the actual effects will be. For overclockers it's great that two out of the three new processors are unlocked.
The AMD A10-7850K is a bit more expensive than the AMD A10-6800K, £128 compared to £110. If you look at the price/performance with current software, that 6800K is arguably more appealing in terms of price. If you want to future-proof your system and are curious about what the new HSA features can do with future software versions, then it's not a huge extra investment for the new A10-7850K.
AMD compares its new processor to the Intel Core i5 4670K (even if the Core i5 4570 is a fairer match), and if you want to assemble an affordable PC without dedicated graphics card, then the Kaveri is indeed the best choice. It's fast enough for gaming, and your system will be prepared for the (hopeful) future of more GPU-accelerated software. If you plan on buying a separate graphics card, we would recommend the Core i5.