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Intel Core i5-6400 review



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Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400
  • Intel Core i5-6400


Our Score:



  • Solid multi-threaded performance
  • Cheapest Core i5 chip available
  • Decent temperatures and power consumption


  • Disappointing single-core speed
  • Little overclocking potential

What is the Intel Core i5-6400?

The Core i5-6400 sits squarely in the middle of Intel's mainstream desktop processor range. Packing the latest Skylake architecture and 14nm manufacturing process as the company's flagship Core i7 6700K it has everything you need to make a powerful and power-frugal PC.

It will be a touch slower but then that's reflected in its far more palatable £140 price.

Intel Core i5-6400 – Specs and Design

The Core i5-6400 is the most affordable standard chip from the Skylake Core i5 range. That means it’s still got most of the assets that pricier Core i5 parts have: it's got four physical cores, 1MB of L2 cache and 6MB of L3 cache.

Related: The Best Z170 Motherboards

Intel Core i5-6400

The big difference between the Core i5-6400 and pricier chips in this range comes is clock speed – the key department where Intel cuts back in order to make cheaper processors. The i5-6400 runs at a standard 2.7GHz and can use Turbo Boost to improve two of its cores to a top speed of 3.3GHz. The Core i5-6600K, meanwhile, starts at 3.5GHz and has a Turbo peak of 3.9GHz.

The other noticeable differences comes in power consumption. The i5-6400 is rated for 65W, which is the same as other standard Core i5 Skylake parts – but the i5-6600K, which has a higher speed and is properly unlocked for overclocking, demands a peak of 91W from the PSU.

That isn’t necessarily a bad thing. The i5-6400 isn’t a K-edition chip unlocked for overclocking - the chance to tweak is only limited to certain boards with the right BIOS - but its more modest power demands means it’ll be absolutely fine beneath Intel’s stock cooler – something that can’t always be said for overclocked K-edition models.

The Core i5-6400 deploys Intel’s HD Graphics 530 integrated core. In this chip the GPU runs at between 350MHz and 950MHz, which means it’s the weakest of any standard-power Skylake Core i5 part – the rest have top speeds of either 1,050MHz or 1,150MHz.

The new core supports DirectX 11.2 but not DirectX 12, and it’s got 48 shaders and 8 ROPs to produce pixel and texture fillrates of 2.8Gpixels/s and 5.6Gtexel/s. That’s a leap over older integrated cores, but it’s still some distance short of even the most modest current-generation AMD and Nvidia discrete graphics cards.

The Core i5-6400’s main competition comes from that i5-6600K, which is pricier but only by £50, and it is more powerful and has serious overclocking potential. Alternatively there's AMD’s FX-8350 Black Edition. That chip is a few pounds cheaper, and it still has four cores that can handle eight concurrent threads. Its clock speeds are faster, with stock and Turbo speeds of 4GHz and 4.2GHz, and it’s got 8MB of cache – two more than the i5-6400.

AMD’s chip has a higher power requirement of 125W, which is poor, but those chips do use the same socket as older AMD parts – so upgrades are potentially more affordable.

Intel Core i5-6400 – The Skylake Ecosystem

Skylake doesn’t just herald a new range of processors – Intel has released a new socket and chipset alongside these chips. The wealth of new hardware is a double-edged sword: it means upgrading to the new processors is more expensive, but it ushers in a range of new features.

The Z170 chipset makes several key changes designed to future-proof PCs. It has many more PCIe 3.0 lanes than previous chipsets – twenty in total – which means there’s more bandwidth available for graphics cards, PCIe-based storage devices and Thunderbolt peripherals.

There’s more support for USB 3.0, better networking options, and Thunderbolt 3.0 debuts here – along with better overclocking options.

Related: The Greatest M.2 SSDs

Intel Core i5-6400

There are other chipsets that have more restrictive feature sets. Parts like H170, B150 and H110 don’t support multiplier-based overclocking, and include fewer USB 3.0 connections. They also have lesser support for PCIe 3.0 slots, with fewer lanes – and some don’t support RAID options for storage.

The arrival of a new socket and chipset also means the market is flooded with new motherboards. Even the cheapest new boards have more features than older models, from PCIe 3.0 slots to M.2 SSD connectors, and they tend to have more USB 3 and SATA connectors too – perfect for taking advantage of Z170’s bandwidth improvements.

Related: Top GPUs

Z170-based boards aren’t cheap. The most affordable start at just over £80, and for that money you’ll get a more basic feature set: fewer PCIe slots and USB connectors, less likelihood of M.2 storage support, and a more modest backplate. At the top end of the market are extreme gaming and overclocking boards that cost over £200 – they come with every port, slot and connector imaginable, as well as on-board buttons, displays and overclocking features.

Boards with the H170, B150 and H110 chipsets are far more affordable. Slabs with the H110 chipset cost less than £60, and most boards with H170 and B150 come in under £100.

Apis Bull

January 12, 2016, 8:48 am

i5 aren't hyper threaded sadly, and only have 4 cores and 4 threads. i3 and i7 are, with 2 cores / 4 threads, and 4 cores / 8 threads respectively. (In the main, as there are i7 with 6 cores etc.)


January 12, 2016, 10:27 am

I must say this review is pretty ropey. For a start, on page 2 it says you're testing the Core i7-6700K. I thought this was the i5-6400 review?
Also, some benchmark comparisons, actual tangible figures for the comparisons you made would be nice. Maybe a few graphs showing where the i5-6400 sites alongside the other models you chose to test.

It is a shame this is outpaced by an older i3 model in some tests, and the GPU is badly under spec.


January 12, 2016, 3:07 pm

No review of overclocking using the new bus speed unlock?


January 13, 2016, 12:05 am

Yeah, this you mean... http://www.bit-tech.net/blo...

Bad Dog

February 3, 2016, 7:27 am

Do not get an i3 for gaming. It only has 2 cores and some games will not run on that cpu. Far Cry 4 will not run on an i3 it will not.

Dipak chavda

February 29, 2016, 6:30 am

I am as a profession Software Engg and I want to assemble new PC. Can anyone suggest me good configuration. I am generally using Netbeans, firefox, skype and some other heavy loaded softwares for programming and communications purpose. I am really confusing. I would like to go for Intel with affordable price. This time I would like to assemble all things by myself.
Can you provide following suggestions?
Processors with best compatible Motherboard, RAM and Is there require cooling liquid for new version of Intel processor for better performance.


March 15, 2016, 11:54 am

Nice review. I upgraded from an FX6300 w 8GB RAM to this and faster 8GB RAM and the difference in time to load previews of raws and to switch between previews as well as add and remove effects in DXO Pro (10) is around twice as fast. Storing all raws being edited on an SSD made almost no perceptible difference, in contrast.


July 8, 2016, 11:27 pm

Have you considered overclocking it? my overclocked i5 6400 gets a 729 CB.


July 8, 2016, 11:28 pm

How much is your budget?

Allan Pôu

September 2, 2016, 6:20 pm

here you go! :) https://www.youtube.com/wat...

Bad Dog

September 6, 2016, 9:59 pm

If you have hacks and the best possible video card available. The card retails for 330 dollars. Then yes you can play it. However most people with an i3 wont have the best possible video card. They will own a midrange video card. If your penny pinching with an i3 I cant see how you would have enough cash for an upgraded video card and power supply. I still stand by my statement that overall if your wanting to play games the i3 just isnt that great. Your much better off getting an i5.

Allan Pôu

September 7, 2016, 7:52 am

In my opinion, i3 6320 (3.9ghz) is a great choice since when you combine it with 2.133 mhz RAM you cant get almost the same results of an i5 4460 and get a better video card with the money left. Plus, a mobo with new socket lga1151 and DDR4.

vanja modrusan

October 5, 2016, 2:18 pm

Hello, I would appreciate some honest opinion about this configuration.
I would like to have a gaming but also a PC for every day tasks. this I found online in Croatia. IT cost is around 800€. I would love to use it with oculus rift VR
CPU: Intel Skylake i5 6400 Soc.1151
Hladnjak: Knight
Matična ploča: H110 Soc.1151
Grafička kartica: Nvidia GeForce GTX 1060 6GB GDDR5
Memorija: 8GB DDR4
Tvrdi disk1: HDD 1TB
Kučište: Knight
Optički uređaj: DVD-RW Dual Layer, SATA
Napajanje: Fractal 600W
Zvuk: 7.1 channel audio
Ostalo: PCI-express, SATAIII, USB3.0, LAN 10/100/1000MB

Cliff Harald

October 6, 2016, 11:59 pm

Far Cry needs 4 threads not 4 cores. The i3 has 4 threads. But CPUs like the Pentium G does not.

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