Intel Core i5-8400H vs Intel Core i5-8257U

Intel Core i5-8400H

► remove Intel 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

► remove

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 i5-8400HIntel Core i5-8257U
Intel Core i5Intel Core i5
Coffee LakeCoffee Lake
: Core i5 Coffee Lake
Intel Core i5-9400H (compare)2500 - 4300 MHz4 / 88 MB
» Intel Core i5-8400H2500 - 4200 MHz4 / 88 MB
Intel Core i5-9300H (compare)2400 - 4100 MHz4 / 88 MB
Intel Core i5-8300H (compare)2300 - 4000 MHz4 / 88 MB
Intel Core i5-8269U (compare)2600 - 4200 MHz4 / 86 MB
Intel Core i5-8279U (compare)2400 - 4100 MHz4 / 86 MB
Intel Core i5-8259U (compare)2300 - 3800 MHz4 / 86 MB
Intel Core i5-8257U1400 - 3900 MHz4 / 86 MB
Intel Core i5-9400H (compare)2500 - 4300 MHz4 / 88 MB
Intel Core i5-8400H2500 - 4200 MHz4 / 88 MB
Intel Core i5-9300H (compare)2400 - 4100 MHz4 / 88 MB
Intel Core i5-8300H (compare)2300 - 4000 MHz4 / 88 MB
Intel Core i5-8269U (compare)2600 - 4200 MHz4 / 86 MB
Intel Core i5-8279U (compare)2400 - 4100 MHz4 / 86 MB
Intel Core i5-8259U (compare)2300 - 3800 MHz4 / 86 MB
» Intel Core i5-8257U1400 - 3900 MHz4 / 86 MB
2500 - 4200 MHz1400 - 3900 MHz
256 KB256 KB
1 MB1 MB
8 MB6 MB
4 / 84 / 8
45 15
14 14
FCBGA1440FCBGA1528
Dual-Channel DDR4 Memory Controller, HyperThreading, AVX, AVX2, Quick Sync, Virtualization, AES-NIDual-Channel DDR4 Memory Controller, HyperThreading, AVX, AVX2, Quick Sync, Virtualization, AES-NI, Intel SSE4.1, Intel SSE 4.2
iGPUIntel UHD Graphics 630 (350 - 1100 MHz)Intel Iris Plus Graphics 645 (300 - 1050 MHz)
Intel Core i5 8400HIntel Core i5 8257U
100 °C

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* Smaller numbers mean a higher performance
1 This benchmark is not used for the average calculation

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Redaktion, 2017-09- 8 (Update: 2017-09-11)