Intel Core i5-8400H vs Intel Core i5-8257U vs Intel Core i9-9980HK

Intel Core i5-8400H

The Intel Core i5-8400H is a high-end processor for laptops with four cores based on the Coffee Lake architecture and will be announced early 2018. The processor clocks at between 2.5 and 4.2 GHz (4.1 with 4 cores) and can execute up to eight threads simultaneously thanks to Hyper-Threading. According to Intel, the CPU is manufactured in an improved 14nm (14nm++) process.

The Coffee Lake architecture is similar to Kaby Lake and differs only in the amount of cores (now six cores for the high end versions) and the improved 14nm process (14nm++ according to Intel).

Performance

The Intel Core i5-8400H should perform similar as the older Core i7-7920HQ (3.1 - 4.1 GHz). The faster Coffee Lake CPUs, like the Core i7-8750H offers two additional cores and is therefore up to 50% faster in multithreaded benchmarks. Still, the performance of the i5-8400H should be sufficient for even demanding applications and games.

Graphics

The integrated Intel UHD Graphics 630 iGPU is supposed to offer a slightly higher performance as its clock rate has been increased by 50 MHz (rumored). The architecture is identical to that of the Intel HD Graphics 630. We do expect a performance improvement, but as a low-end solution it will probably only display current games smoothly at reduced details - if at all.

Power Consumption

Intel specifies the TDP with 45 watts and therefore the i5 is only suited for big laptops with good cooling solutions. Using cTDP-down, the CPU can also be configured to 35 Watt resulting in a reduced performance.

Intel Core i5-8257U

The Intel Core i5-8257U is a quad-core SoC for notebooks based on the Coffee Lake architecture that was announced in the new entry level MacBook Pro 13 in mid 2019. Compared to its predecessor, the CPU is now a quad-core with Hyperthreading support for the execution of up to 8 threads simultaneously. The base frequency is only 1.4 GHz, but the Turbo goes all the way up to 3.9 GHz. It is also equipped with an Intel Iris Plus Graphics 645 GPU with 128 MB eDRAM, 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 with FinFET transistors.

Compared to faster Core i7-8557U model with eDRAM and 15 Watts, the i5-8257U only features 6 MB smart cache and the slowest clock of the Iris Plus GPU.

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 relative high Turbo Boost clock, the single thread performance should be very good, but still behind the faster i7 model. The short burst all core performance is clearly better compared to the old dual core predecessors thanks to the additional cores. In sustained workloads, the performance is usually limited by the TDP and cooling. In these workloads the difference to the Core i7 should be also smaller.

Graphics

The integrated Intel Iris Plus 645 Graphics is the GT3e model of the Coffee 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 with FinFET transistors, which improves the efficiency even further. Intel specifies the TDP with 15 Watts and therefore suited for thin and light laptops.

Intel Core i9-9980HK

The Intel Core i9-9980HK is a high-end processor for laptops with eight cores based on the Coffee Lake architecture (2019 refresh, CFL-HR). The processor clocks at between 2.4 - 5 GHz and can execute up to sixteen threads simultaneously thanks to Hyper-Threading. The 5 GHz can only be reached using the "Thermal Velocity Boost" which allows one core to boost to 5 GHz (+100 MHz) as long as the CPU temperature is below 50°C. Multiple cores can be boosted +100 MHz? below 50°C (not verified). Compared to the predecessor, the Core i9-8950HK, the 9980H is based on the same architecture but offers 2 more cores and higher clock speeds (boost).

According to Intel, the CPU is manufactured in an improved 14nm (14nm++) process. The i9-9980HK is the fastest model of the Coffee-Lake-H (refresh) series at the time of announcement and offers an unlocked multiplier for overclocking of the CPU.

The Coffee Lake architecture is similar to Kaby Lake and differs only in the amount of cores (now max. eight cores for the high end versions) and the improved 14nm process (14nm++ according to Intel).

Performance

Due to the two additional cores, performance has increased by almost 33% compared to a similar clocked 6-core processor. According to first benchmarks, the mobile variant can reach the performance of the Core i9-9900K if the cooling is sufficient.

Graphics

The integrated Intel UHD Graphics 630 iGPU is supposed to offer a slightly higher performance as its clock rate has been increased by 50 MHz. The architecture is identical to that of the Intel HD Graphics 630. We do expect a performance improvement, but as a low-end solution it will probably only display current games smoothly at reduced details - if at all.

Power Consumption

Intel specifies the TDP with 45 watts and therefore the i9 is only suited for big laptops with good cooling solutions.