Intel Core i5-9400F vs Intel Core i5-8257U vs Intel Core i3-8109U

The Intel Core i5-9400F is a six-core desktop processor based on the Coffee Lake architecture introduced in October 2018 along with the flagship Intel Core i9-9900K. The processor clocks at 2.9-4.1 GHz and can process up to 6 threads simultaneously. The Intel Core i5-9400F is manufactured in the improved 14-nm process (14nm++).

Performance

Compared to the Intel Core i5-8400, the performance could only be increased slightly. Performance increases of up to 10 percent can be expected. Both processors (old and new) still do not offer hyperthreading. The performance increase therefore only adds up to small architecture improvements and a slightly higher basic and turbo clock rate. This CPU is suitable for everyday office use, which does not require large coolers due to the low waste heat. But games are also among the application areas, because in games the Intel Core i5-9400F clearly beats the Intel Core i3-9100F. Here the six cores are paying off in the meantime. 

Graphics unit

The Intel Core i5-9400F is a processor without integrated graphics unit. If you value an iGPU, you should take a closer look at the Intel Core i5-9400, as it offers the entry level Intel UHD Graphics 630.

Power consumption

Intel puts the Thermal Design Power (TDP) at 65 watts. This means there is no need for large cooling systems, which also allows installation in very compact housings.

The Intel Core i3-8109U is a dual-core SoC for notebooks based on the Coffee Lake architecture and was announced in April 2018. Compared to its predecessor Core i3-7167U, the CPU now supports Turbo boost with up to 3.6 GHz. Thanks to Hyperthreading the CPU can execute up to 4 threads simultaneously. It is also equipped with an Intel Iris Plus Graphics 655 GPU with 128 MB eDRAM (but with 300 - 1050 MHz it is the slowest Iris Plus), a dual-channel memory controller (DDR4) as well as VP9 and H.265 video decoding as well as encoding. The chip is still manufactured in a 14nm++ process (3rd generation) with FinFET transistors.

Architecture

Intel basically uses the same micro architecture compared to Kaby Lake, 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 Turbo Boost, the processor performance should be a bit above the old Core i7-7500U (max. 3.5 GHz, 15 Watt). Therefore the Core i3-8109U should be fine for most applications. Some games however already need four real cores for optimal performance (paired with a dedicated GPU e.g.).

Graphics

The integrated Intel Iris Plus 655 Graphics is the GT3e model of the Kaby Lake GPU (Intel Gen. 9.5). It has 48 Execution Units running at 300-1050 MHz  and the performance is comparable to a GeForce 930M or 940MX thanks to fast eDRAM cache. However, there aren't any significant improvements compared to the old Iris Plus 650, so modern games can often not be played smoothly or only at the lowest or medium settings, respectively.

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

Power Consumption

The chip is manufactured in an improved 14nm process (14nm++, 3rd generation of 14nm) with FinFET transistors, which improves the efficiency even further. Intel specifies the TDP with 28 Watts, which can be reduced to 23 Watts (cTDP Down) depending on the usage scenario. The TDP is pretty high compared to the common 15-Watt TDP for quad-core processors, but allows a better utilization of CPU and GPU Turbo.