In terms of overall gaming performance, the Intel Core i7-2600 4-Core 3.40GHz is massively better than the AMD APU A6-6400K when it comes to running the latest games. This also means it will be less likely to bottleneck more powerful GPUs, allowing them to achieve more of their gaming performance potential.
The APU A6-6400K was released over a year more recently than the Core i7-2600 4-Core, and so the APU A6-6400K is likely to have better levels of support, and will be more optimized for running the latest games.
The Core i7-2600 4-Core has 2 more cores than the APU A6-6400K. With 4 cores, the Core i7-2600 4-Core is much less likely to struggle with the latest games, or bottleneck high-end graphics cards when running them.
More important for gaming than the number of cores and threads is the clock rate. Problematically, unless the two CPUs are from the same family, this can only serve as a general guide and nothing like an exact comparison, because the clock cycles per instruction (CPI) will vary so much.
The APU A6-6400K and Core i7-2600 4-Core are not from the same family of CPUs, so their clock speeds are by no means directly comparable. Bear in mind, then, that while the APU A6-6400K has a 0.5 GHz faster frequency, this is not always an indicator that it will be superior in performance, despite frequency being crucial when trying to avoid GPU bottlenecking. In this case, however, the difference is enough that it possibly indicates the superiority of the Core i7-2600 4-Core.
Aside from the clock rate, the next-most important CPU features for PC game performance are L2 and L3 cache size. Faster than RAM, the more cache available, the more data that can be stored for lightning-fast retrieval. L1 Cache is not usually an issue anymore for gaming, with most high-end CPUs eking out about the same L1 performance, and L2 is more important than L3 - but L3 is still important if you want to reach the highest levels of performance. Bear in mind that although it is better to have a larger cache, the larger it is, the higher the latency, so a balance has to be struck.
The APU A6-6400K and the Core i7-2600 4-Core have the same L2 cache size, but the APU A6-6400K does not appear to have an L3 cache, so the Core i7-2600 4-Core definitely wins out in this area.
The maximum Thermal Design Power is the power in Watts that the CPU will consume in the worst case scenario. The lithography is the semiconductor manufacturing technology being used to create the CPU - the smaller this is, the more transistors that can be fit into the CPU, and the closer the connections. For both the lithography and the TDP, it is the lower the better, because a lower number means a lower amount of power is necessary to run the CPU, and consequently a lower amount of heat is produced.
The APU A6-6400K has a 30 Watt lower Maximum TDP than the Core i7-2600 4-Core (though they were created with the same size 32 nm manufacturing technology). What this means is the APU A6-6400K will consume significantly less power and consequently produce less heat, enabling more prolonged computational tasks with fewer adverse effects. This will lower your yearly electricity bill significantly, as well as prevent you from having to invest in extra cooling mechanisms (unless you overclock).
The Core i7-2600 4-Core has an on-board GPU, which means that it will be capable of running basic graphics applications (i.e., games) without the need for a dedicated graphics card. The APU A6-6400K, however, does not, and you will probably have to look for a dedicated card if you wish to use it at all.
For in-depth GPU comparisons with the Intel HD Graphics 2000 Desktop, click on the following GPU overview comparison icon (visible throughout Game-Debate), and choose a GPU from the list to compare against:
On-board GPUs tend to be fairly awful in comparison to dedicated cards from the likes of AMD or Nvidia, but as they are built into the CPU, they also tend to be cheaper and require far less power to run (this makes them a good choice for laptops). We would recommend a dedicated card for running the latest games, but integrated GPUs are improving all the time and casual gamers may find less recent games perform perfectly acceptably.