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Core i7-8700k vs i5-8400


Description
Both models i7-8700k and i5-8400 are based on Coffee Lake architecture.

Coffee Lake is the second refinement of Intel’s 14nm (Tri-Gate) technology. While it uses LGA1151 socket, it is incompatible with previous generations due to electrical changes in socket’s pins so these CPUs require Z370 chipset. This kind of generation introduced more cores in every range to compete with new AMD’s architecture. Coffee Lake uses DDR4 memory at 2400MHz for i3 and at 2666MHz for i5, i7 CPUs plus iGPU frequency has been increased 50MHz with respect to previous generation.

Using the multithread performance as a reference, the i7-8700k gets a score of 443.8 k points while the i5-8400 gets 289.6 k points.

Summarizing, the i7-8700k is 1.5 times faster than the i5-8400. To get a proper comparison between both models, take a look to the data shown below.

Specs
CPUID
906ea
906ea
Core
Coffee Lake-S
Coffee Lake-S
Architecture
Base frecuency
3.7 GHz
2.8 GHz
Boost frecuency
4.7 GHz
4 GHz
Socket
LGA 1151
LGA 1151
Cores/Threads
6/12
6/6
TDP
95 W
65 W
Cache L1 (d+i)
6x32+6x32 kB
6x32+6x32 kB
Cache L2
6x256 kB
6x256 kB
Cache L3
12288 kB
9216 kB
Date
October 2017
September 2017
Mean monothread perf.
80.6k points
64.98k points
Mean multithread perf.
443.77k points
289.61k points

Non-optimized benchmark
The benchmark in Mode 0 (FPU) measures cpu performance with non-optimized software. It uses the basic µinstructions from the i386 architecture with the i387 floating point unit. This mode is compatible with all CPUs so it's practical to compare very different CPUs
Monothread
i7-8700k
i5-8400
Test#1 (Integers)
4.13k
4.08k (x0.99)
Test#2 (FP)
16.96k
14.96k (x0.88)
Test#3 (Generic, ZIP)
5.56k
4.98k (x0.9)
Test#1 (Memory)
12.85k
10.29k (x0.8)
TOTAL
39.5k
34.31k (x0.87)

Multithread

i7-8700k

i5-8400
Test#1 (Integers)
24.01k
21.54k (x0.9)
Test#2 (FP)
108.69k
85.13k (x0.78)
Test#3 (Generic, ZIP)
36.62k
28.24k (x0.77)
Test#1 (Memory)
9.33k
4.08k (x0.44)
TOTAL
178.64k
139k (x0.78)

AVX2 optimized benchmark
The benchmark in mode III (AVX2), like AVX1, is optimized to used 256 bits registers beside the second version of the Advanced Vector Extensions (AVX). The first AVX2 compatible CPU was released in 2013.
Monothread
i7-8700k
i5-8400
Test#1 (Integers)
31.2k
26.5k (x0.85)
Test#2 (FP)
27.82k
23.11k (x0.83)
Test#3 (Generic, ZIP)
6.57k
5.2k (x0.79)
Test#1 (Memory)
15k
10.16k (x0.68)
TOTAL
80.6k
64.98k (x0.81)

Multithread

i7-8700k

i5-8400
Test#1 (Integers)
202.42k
135.08k (x0.67)
Test#2 (FP)
186.33k
121.49k (x0.65)
Test#3 (Generic, ZIP)
44.96k
27.53k (x0.61)
Test#1 (Memory)
10.05k
5.5k (x0.55)
TOTAL
443.77k
289.61k (x0.65)

Performance/W
i7-8700k
i5-8400
Test#1 (Integers)
2131 points/W
2078 points/W
Test#2 (FP)
1961 points/W
1869 points/W
Test#3 (Generic, ZIP)
473 points/W
424 points/W
Test#1 (Memory)
106 points/W
85 points/W
TOTAL
4671 points/W
4455 points/W

Performance/GHz
i7-8700k
i5-8400
Test#1 (Integers)
6639 points/GHz
6626 points/GHz
Test#2 (FP)
5919 points/GHz
5778 points/GHz
Test#3 (Generic, ZIP)
1397 points/GHz
1300 points/GHz
Test#1 (Memory)
3192 points/GHz
2541 points/GHz
TOTAL
17148 points/GHz
16245 points/GHz

Monothread performance graph
Monothread performance graphics gives the performance vs time. They are useful to measure the time it takes to the CPU to reach the maximum performance.

Usually, CPU's performance will be steady during these tests but if it has a slow frequency strategy, the first samples will show a lower score.


Test#1 (Integers) [points vs time]

grafica bm.hardlimit.com


Test#2 (FP) [points vs time]

grafica bm.hardlimit.com


Test#3 (Generic, ZIP) [points vs time]

grafica bm.hardlimit.com


Test#1 (Memory) [points vs time]

grafica bm.hardlimit.com

Multithread performance graph
Multithread graphs measure the performance against a heavy load during certain time.

If CPU's TDP doesn't limit the frequency and the machine is properly cooled, performance should remain steady vs time. Otherwise, the performance score will oscillate or decrease over time.


Test#1 (Integers) [points vs time]

grafica bm.hardlimit.com


Test#2 (FP) [points vs time]

grafica bm.hardlimit.com


Test#3 (Generic, ZIP) [points vs time]

grafica bm.hardlimit.com


Test#1 (Memory) [points vs time]

grafica bm.hardlimit.com

Hardlimit Benchmark Central - Ver. 3.11.4