Home > CPU Comparison > Core i7 6700K or Core i5 8400: what's better?

Intel Core i7 6700K vs i5 8400

31 out of 100
Intel Core i7 6700K
VS
30 out of 100
Intel Core i5 8400
Intel Core i7 6700K
Intel Core i5 8400

We compared two desktop CPUs: the 4.0 GHz Intel Core i7 6700K with 4-cores against the 2.8 GHz i5 8400 with 6-cores. On this page, you'll find out which processor has better performance in benchmarks, games and other useful information.

  1. Review
  2. Differences
  3. Performance
  4. Specs
  5. Comments

Review

General overview and comparison of the processors
Single-Core Performance
Performance in single-threaded apps and benchmarks
Multi-Core Performance
Measure performance when all cores are involved
Power Efficiency
The efficiency score of power consumption
The "iGPU" and "Power Efficiency" have a minor impact on the NanoReview Score for desktop CPU.
NanoReview Final Score
Choose your main usage scenario to recalculate the Final Score and see which CPU suits your needs.
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Value for money (Beta)

Global average CPU prices are used by default! For better accuracy, enter your current prices and click “Calculate".
Currency
VS
8.8
(Bad)
Value Index
60.0
(Average)

Key Differences

What are the key differences between 8400 and 6700K
Advantages of Intel Core i7 6700K
  • Unlocked multiplier
  • 5% higher Turbo Boost frequency (4.2 GHz vs 4 GHz)
Advantages of Intel Core i5 8400
  • Supports up to 128 GB DDR4-2666 RAM
  • Has 2 more physical cores
  • Newer - released 2 years and 2 months later
  • Around 7.5 GB/s (22%) higher theoretical memory bandwidth

Test in Benchmarks

Comparing the performance of CPUs across various tasks
CPU:
Core i7 6700K
vs
Core i5 8400

Cinebench

Reputable cross-platform benchmark for high-performance processors
Cinebench 2024 (Single)
Cinebench 2024 (Multi)
Submit your benchmark results

GeekBench v6

The new version of this benchmark emulates common operations often used in real-world apps
Geekbench 6 (Single-Core)
Core i7 6700K +7%
1512
Core i5 8400
1414
Geekbench 6 (Multi-Core)
File compression 428.4 MB/sec 392.9 MB/sec
Clang compilation 35.7 Klines/sec 36 Klines/sec
HTML 5 Browser 116.8 pages/sec 115 pages/sec
PDF Renderer 168.3 Mpixels/sec 156.8 Mpixels/sec
Text processing 152.1 pages/sec 139 pages/sec
Background blur 28 images/sec 33.8 images/sec
Photo processing 50.9 images/sec 49.9 images/sec
Ray tracing 6.53 Mpixels/sec 5.93 Mpixels/sec
Sources: GeekBench [1], [2] – 1195 & 1184 samples

PassMark

Synthetic test that focuses on raw computational performance for low-level functions
Passmark CPU (Single-Core)
Core i7 6700K +6%
2497
Core i5 8400
2366
Passmark CPU (Multi-Core)
Core i7 6700K
8939
Core i5 8400 +3%
9232
Integer math 28.2 GOps/sec 25.6 GOps/sec
Floating point math 17.4 GOps/sec 22 GOps/sec
Find prime numbers 30M Primes/sec 37M Primes/sec
Random string sorting 15.8M Strings/sec 15.9M Strings/sec
Data encryption 3.1 GBytes/sec 2.8 GBytes/sec
Data compression 125.7 MBytes/sec 129.6 MBytes/sec
Physics 636 Frames/sec 634 Frames/sec
Extended instructions 8.3B Matrices/sec 11.5B Matrices/sec
Sources: PassMark [3], [4] – 19003 & 9637 samples

Blender

3D rendering test that measures CPU performance in 3D modeling tasks (uses all cores)
Blender CPU
Core i7 6700K +5%
81.55
Core i5 8400
77.38

Performance Per Watt

Shows the score you get per each watt of PL1 TDP
Cinebench 2024 / Watt 3.1 PPW 4.8 PPW
Geekbench 6 Multi / Watt 55.7 PPW 78.2 PPW
Passmark CPU Mark / Watt 98.2 PPW 142 PPW
Blender / Watt 0.9 PPW 1.19 PPW
These are rough calculations, as most CPUs surpass PL1 TDP wattage even in multicore workloads.

Recent User Tests

The latest benchmark tests that have been submitted by users
Intel Core i7 6700K
DateBenchmarkResult
📘 2025-11-08 (CRSTN)Cinebench 202467 / 328
📘 2024-09-27 (A)Cinebench 202454 / 279
Add View all (2)
Intel Core i5 8400
No benchmark results yet
Add

Specifications

Full technical specification of Intel Core i7 6700K and i5 8400

General

Vendor Intel Intel
Released August 5, 2015 October 5, 2017
Type Desktop Desktop
Instruction Set x86-64 x86-64
Codename Skylake Coffee Lake
Model number i7-6700K i5-8400
Integrated GPU HD Graphics 530 UHD Graphics 630
Rival Equivalent - - AMD Ryzen 5 2400G
Successor - Intel Core Ultra 7 270K Plus - Intel Core Ultra 5 225

CPU

Performance Cores
P-Cores 4 6
P-Threads 8 6
Base Frequency (P) 4.0 GHz 2.8 GHz
Turbo Boost Frequency (P) 4.2 GHz 4 GHz
Total
Total Cores 4 6
Total Threads 8 6
Bus Frequency 100 MHz 100 MHz
Multiplier 40x 28x
Bus Bandwidth 8 GT/s 8 GT/s
L1 Cache 64K (per core) 64K (per core)
L2 Cache 256K (per core) 256K (per core)
L3 Cache 8MB (shared) 9MB (shared)
Unlocked Multiplier Yes No

Package

Transistors 1.75 billions -
Fabrication Process 14 nm 14 nm
TDP (PL1) 91 W 65 W
Socket LGA-1151 LGA-1151
Peak Temperature - 100°C
Desktop CPU ranking (178th and 181st place)

iGPU

Integrated Graphics Intel HD Graphics 530 Intel UHD Graphics 630
GPU Base Clock - 350 MHz
GPU Boost Clock 1150 MHz 1050 MHz
Shading Units - 192
TMUs - 24
ROPs - 3
Execution Units - 24
TGP - 15 W
iGPU FLOPS
Core i7 6700K
n/a
Core i5 8400
0.4 TFLOPS
See: Intel UHD Graphics 630 benchmarks

Memory Support

Memory Types - DDR4-2133
- DDR3L-1600		 - DDR4-2666
Max. Memory Size 64 GB 128 GB
Memory Channels 2 2
Max. Memory Bandwidth 34.1 GB/s 41.6 GB/s
ECC Support No No

Misc

Official Site Intel Core i7 6700K official page Intel Core i5 8400 official page
PCI Express Version 3.0 3.0
PCI Express Lanes 16 16

Cast your vote

Choose between two processors
67 (52.3%)
61 (47.7%)
Total votes: 128

Competitors

1. Intel Core i7 6700K vs Intel Core i5 12600K
Compare other CPUs (460+)

Comments

So which CPU will you choose: Intel Core i5 8400 or i7 6700K?
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