Intel Core i5-6400 vs Intel Core i5-6600K vs Intel Core i5-6400T

Intel Core i5-6400

The Intel Core i5-6400 is a desktop class quad-core CPU. The additional 4 threads are not available to the CPU as it is missing the HyperThreading support. The i5-6400 is based on Skylake architecture and clocks within the 2.7 GHz to 3.3 GHz range. 

Intel Core i5-6600K

The Intel Core i5-6600K is a high-end quad-core desktop processor based on the Skylake architecture, which was announced in August 2015. The CPU, which is manufactured in a 14 nm process, runs at 3.5 up to 3.9 GHz (2 cores: 3.8 GHz, 3 cores: 3.7 GHz, 4 cores: 3.6 GHz) and – contrary to the i7-series – does not support Hyperthreading. Being a so called "K"-model, the Core i5-6600K has a free multiplier and can be easily overclocked. 

Performance

Because of the slightly slower clocks, the smaller L3-cache (6 instead of 8 MB) as well as the missing Hyperthreading support, the Core i5-6600K is about 10-30 percent slower than the top model i7-6700K. The CPU will still handle demanding applications and games without any problems.

Graphics

Graphics are handled by the integrated Intel HD Graphics 530 with 24 EUs (Execution Units), which is clocked at 350 - 1150 MHz. Compared to the HD Graphics 4600 (Haswell, 20 EUs), the performance is increased by around 25 percent. The overall GPU performance is still low-end, so modern games can, if at all, only be played smoothly with low settings. 

Power Consumption

The TDP was slightly raised from 88 to 91 Watts compared to the predecessor.

Intel Core i5-6400T

The Intel Core i5-6400T is a frugal quad-core desktop processor based on the Skylake architecture, which was announced in August 2015. The CPU, which is manufactured in a 14 nm process, runs at 2.2-2.8 GHz and does not support Hyperthreading (only 4 threads simultaneously).

Architecture

Intel uses Skylake to replace both Broadwell as well as Haswell and therefore uses one core design for all TDP classes between 4.5-45 Watts. Several improvements of the Skylake architecture include bigger Out-to-Order-Buffer, optimizations for pre-fetching as well as bigger gains by Hyperthreading. However, the changes are small for a "Tock" – a new micro architecture – in general, so the per-MHz performance is only between 5-10 % (compared to Haswell) or less than 5 % higher (compared to Broadwell), respectively.

Performance

Depending on the utilization of Hyperthreading, the performance is roughly on par with the old Core i7-2670QM mobile processor (Sandy Bridge, 2.2-2.8 GHz, Hyperthreading), but sometimes also much higher.

Graphics

Graphics are handled by the integrated Intel HD Graphics 530 with 24 EUs (Execution Units), which is clocked at 350 - 950 MHz. Compared to the HD Graphics 4600 (Haswell, 20 EUs), the performance is increased by around 25 percent. The overall GPU performance is still low-end, so modern games can, if at all, only be played smoothly with low settings.

Power Consumption

Intel specifies the TDP with 35 Watts, so it can also be used in notebooks (although bigger ones).