Specs:

i5-6600K:
Price: USD$243
Cores: 4 cores 4 threads
Clock Speed: 3.5GHz-3.9GHz
L3 Cache: 6MB
PCIe 3.0 Lanes: 16
TDP: 91W
Memory Support: Dual Channel DDR4-2133, DDR3L-1600

i7-6700K:
Price: USD$350
Cores: 4 core 8 threads
Clock Speed: 4.0GHz-4.2GHz
L3 Cache: 8MB
PCIe 3.0 Lanes: 16
TDP: 91W
Memory Support: Dual Channel DDR4-2133, DDR3L-1600

同上代表現差唔得幾遠，用緊Ivy Bridge/Haswell如果唔需要DDR4或者好多PCIe lanes嘅無咩upgrade嘅必要