The AMD A6-6400K is a desktop APU from the Richland series. The chip is produced in a 32nm process and integrates 1 module with 2 CPU cores clocked at 3.9 to 4.1 GHz. 
The 6400K has a Radeon HD 8470D graphics unit and a DDR3-1600 memory controller.

The integrated DirectX 11-compatible Radeon HD 8470D offers only 192 of the 384 shader cores of the Richland chip and a core clock of 800 MHz 

Specification :
Family : AMD A6-Series
Model number : A6-6400K
CPU P/N : AD640KOKHLBOX is a BOXed microprocessor
Frequency : 3900 MHz
Turbo frequency : 4100 MHz
Boosted P states :
#1: 4100 MHz, 1.275V
#2: 4000 MHz, 1.15V
Package : 904-pin organic lidded micro Pin Grid Array 
Socket : Socket FM2
Size : 4 x 4 cm
Weight : 39 gr
Microarchitecture : Piledriver
Processor core : Richland
Manufacturing process : 0.032 micron
Data width : 64 bit
The number of cores : 2
The number of threads : 2
Level 1 cache size :
~64 KB 2-way set associative shared instruction cache
~2 x 16 KB 4-way set associative data caches
Level 2 cache size : 1 MB 16-way set associative shared exclusive cache
Cache latency : 3 (L1 cache)
Multiprocessing : Uniprocessor
Integrated graphics GPU Type : Radeon HD 8470D
Shader cores : 192
Base frequency (MHz) : 800
Memory controller : 1
Memory channels : 2
Supported memory : DDR3-1866
Maximum memory bandwidth (GB/s) : 29.9
Maximum operating temp : 70o C
Thermal Design Power : 65 Watt
Warranty : 3 Years