Intel Core i5-7500T vs Intel Core i7-3940XM vs Intel Core i7-7700K

Intel Core i5-7500T

The Intel Core i5-7500T is a power efficient desktop quad-core based on the Kaby Lake architecture. It was announced early 2017 and offers four cores and no HyperThreading (only 4 threads). The CPU clocks between 2.7 and 3.3 GHz. The integrated Intel HD Graphics 630 graphics card offers 24 EUs clocked at 350 to 1100 MHz. The TDP is specified at only 35 Watt and therefore even lower than mobile HQ quad cores (45 Watt). Thats why the CPU is also used in some laptops.

Intel Core i7-3940XM

The Intel Core i7-3940XM is the fastest quad-core processor for laptops (at the time of introduction in September 2012) an successor of the i7-3920XM. Due to Hyperthreading, the four cores can handle up to eight threads in parallel leading to better utilization of the CPU. Each core offers a base speed of 3.0 GHz but can dynamically increase clock rates with Turbo Boost up to 3.7 GHz (for 4 active cores), 3.8 GHz (for 2 active cores) and 3.9 GHz (for 1 active core). Furthermore, the Extreme CPUs offer an unlocked multiplicator for easy overclocking.

Ivy Bridge is an enhanced die shrink of the Sandy Bridge architecture with improvements on both GPU and CPU performance. The CPUs are produced in 22nm (versus 32nm Sandy Bridge CPUs) and are the first to introduce 3D transistors for increased energy efficiency when compared to similarly clocked Sandy Bridge processors. Other new features are integrated PCI Express 3.0 and  DDR3(L)-1600 support.

The performance of the Core i7-3940XM should be slightly above a similarly clocked Sandy Bridge processor due to slight architectural improvements. Because of the higher clock speed, the former champion Core i7-3920XM should be outperformed by about 3%.

The integrated Intel HD Graphics 4000 offers 16 Execution Units (EUs) clocked at 650 MHz up to 1350 MHz with Turbo Boost, making it the fastest variant.

The XM CPUs are rated at a TDP of 55 Watts including graphics card and memory controller and therefore 10 Watt higher than the other quad-core models.  Therefore, the CPU is well-suited for laptops 17-inches or greater.

Intel Core i7-7700K

The Intel Core i7-7700K is a fast quad-core processor for desktops based on the Kaby Lake architecture and was announced in January 2017. It is the top model of the consumer Kaby-Lake-H series at the time of the announcement. Besides four cores including Hyper-Threading (8 threads) support running at 4.2 - 4.5 GHz, the processor is also equipped with the HD Graphics 630 GPU as well as a dual-channel memory controller (DDR3L-1600/DDR4-2400). It is manufactured in a 14nm process with FinFET transistors.

Architecture

Intel basically uses the same micro architecture compared to Skylake, so the per-MHz performance does not differ. The manufacturer only reworked the Speed Shift technology for faster dynamic adjustments of voltages and clocks, and the improved 14nm process allows much higher frequencies combined with better efficiency than before.

Performance

Thanks to the 200 (base) and 300 MHz (Boost) higher clock speed, respectively, the i7-7700K is a few percent faster than the old Skylake Core i7-6700K that offers the same per-MHz performance. Therefore, it is a very fast quad-core CPU that offers sufficient performance for all tasks.

Graphics

The integrated Intel HD Graphics 630 has 24 Execution Units (similar to previous HD Graphics 530) running at 350 - 1150 MHz. The performance depends a lot on the memory configuration; it should be comparable to a dedicated Nvidia GeForce 920M in combination with fast DDR4-2133 dual-channel memory.

Contrary to Skylake, Kaby Lake now supports hardware decoding for H.265/HEVC Main 10 with a 10-bit color depth as well as Google's VP9 codec. The dual-core Kaby Lake processors, which were announced in January, should also support HDCP 2.2.

Power Consumption

The chip is manufactured in an improved 14nm process with FinFET transistors, which improves the efficiency slightly. Intel still specifies the TDP with 91 Watts, which is a lot more than the 45 Watts of the mobile Kaby-Lake-H CPUs.