CPUBoss Review Our evaluation of 6600K vs 6400 among all CPUs


Benchmark performance using all cores

PCMark 8 Home 3.0 Accelerated, PassMark and 1 more

Single-core Performance

Individual core benchmark performance

PassMark (Single Core), Geekbench 3 Single Core and 1 more

Integrated Graphics

Integrated GPU performance for graphics

Sky Diver and Cloud Gate

Integrated Graphics (OpenCL)

Integrated GPU performance for parallel computing

CompuBench 1.5 Bitcoin mining and 4 more

Performance per Watt

How efficiently does the processor use electricity?

Sky Diver, Cloud Gate, CompuBench 1.5 Bitcoin mining and 11 more


Are you paying a premium for performance?

Sky Diver, Cloud Gate, CompuBench 1.5 Bitcoin mining and 11 more


CPUBoss Score

Combination of all six facets

Intel Core i5 6600K 

CPUBoss recommends the Intel Core i5 6600K  based on its performance, single-core performance and value.

See full details

Cast your vote Do you agree or disagree with CPUBoss?

Thanks for adding your opinion. Follow us on Facebook to stay up to date with the latest news!

Intel Core i5 6600K

CPUBoss Winner
Front view of Intel Core i5 6600K

Differences What are the advantages of each

Front view of Intel Core i5 6600K

Reasons to consider the
Intel Core i5 6600K

Report a correction
Is unlocked Yes vs No Somewhat common; An unlocked multiplier allows for easier overclocking
Significantly higher clock speed 3.5 GHz vs 2.7 GHz Around 30% higher clock speed
Higher turbo clock speed 3.9 GHz vs 3.3 GHz Around 20% higher turbo clock speed
Significantly better turbo clock speed 1,150 MHz vs 950 MHz More than 20% better turbo clock speed
Better overclocked clock speed (Air) 4.54 GHz vs 3.69 GHz Around 25% better overclocked clock speed (Air)
Better geekbench 3 single core score 3,134 vs 2,428.5 Around 30% better geekbench 3 single core score
Better performance per dollar 1.36 pt/$ vs 1.09 pt/$ Around 25% better performance per dollar
Front view of Intel Core i5 6400

Reasons to consider the
Intel Core i5 6400

Report a correction
Lower typical power consumption 52.81W vs 73.94W Around 30% lower typical power consumption
Higher Maximum operating temperature 71 °C vs 64 °C More than 10% higher Maximum operating temperature
Lower annual home energy cost 15.66 $/year vs 21.92 $/year Around 30% lower annual home energy cost
Lower annual commercial energy cost 56.94 $/year vs 79.72 $/year Around 30% lower annual commercial energy cost

Benchmarks Real world tests of Core i5 6600K vs 6400

CompuBench 1.5 (Bitcoin mining) Data courtesy CompuBench

Core i5 6600K
35.31 mHash/s
Core i5 6400
24.14 mHash/s

CompuBench 1.5 (Face detection)

Core i5 6600K
25.92 mPixels/s
Core i5 6400
19.56 mPixels/s

CompuBench 1.5 (T-Rex) Data courtesy CompuBench

Core i5 6600K
1.91 fps
Core i5 6400
1.16 fps

GeekBench 3 (Multi-core) Data courtesy Primate Labs

Core i5 6400

GeekBench 3 (Single core) Data courtesy Primate Labs

Core i5 6400

GeekBench 3 (AES single core) Data courtesy Primate Labs

Core i5 6600K
209.7 MB/s
Core i5 6400
155.25 MB/s

PassMark Data courtesy Passmark

PassMark (Single Core)

Specifications Full list of technical specs


Core i5 6600K  vs
Clock speed 3.5 GHz 2.7 GHz
Turbo clock speed 3.9 GHz 3.3 GHz
Cores Quad core Quad core
Is unlocked Yes No


Has a NX bit Yes Yes
Supports trusted computing No No
Has virtualization support Yes Yes
Instruction set extensions
Supplemental SSE3
AVX 2.0
Supports dynamic frequency scaling Yes Yes

power consumption

TDP 91W 65W
Annual home energy cost 21.92 $/year 15.66 $/year
Annual commercial energy cost 79.72 $/year 56.94 $/year
Performance per watt 2.4 pt/W 2.63 pt/W
Typical power consumption 73.94W 52.81W


Architecture FSB FSB
Number of links 0 1
Transfer rate 8,000 MT/s 8,000 MT/s


Core i5 6600K  vs
Architecture x86-64 x86-64
Threads 4 4
L3 cache 6 MB 6 MB
L3 cache per core 1.5 MB/core 1.5 MB/core
Manufacture process 14 nm 14 nm
Max CPUs 1 1
Operating temperature Unknown - 64°C Unknown - 71°C


Overclocked clock speed 4.54 GHz 3.69 GHz
Overclocked clock speed (Water) 4.56 GHz 4.46 GHz
Overclocked clock speed (Air) 4.54 GHz 3.69 GHz

integrated graphics

Label Intel® HD Graphics 530 Intel® HD Graphics 530
Number of displays supported 3 3
GPU clock speed 350 MHz 350 MHz
Turbo clock speed 1,150 MHz 950 MHz

memory controller

Memory controller Built-in Built-in
Memory type
Channels Dual Channel Dual Channel
Supports ECC No No
Maximum bandwidth 25,600 MB/s 25,600 MB/s
Maximum memory size 65,536 MB 65,536 MB
Intel Core i5 6600K
Report a correction
Intel Core i5 6400
Report a correction


Showing 9 comments.
Hello. I have the same board and would like for you to email me the bios or send a link to where it is located. I've been looking for this bios everywhere to no avail. Thank you in advance. My email is: deathblameme@gmail.com
Why would anyone even be "leaving voltage on automatic"? Your last sentence should be "heavily modernised" into: "You obviously need to do your homework and use more common sense and take your time when you're overclocking the bus speed, so it's definitely MUCH more TROUBLE than just upping the core multiplier and upping the voltage". Increasing my CPU Core multiplier to 45 and CPU VCore to 1.35 V in order to overclock immediately (!) to 4.5 GHz took me less than 30 seconds flat the very first time I opened the BIOS (I can now do it in under 15 seconds... I know, still slow but with a little practice I reckon I could achieve it in 10 seconds or less), without even having to know (or care) about what BCLK, FCLK, Uncore (Cache/Ring) and the memory frequency were set at. By the way, I showed this to my nephew (who wasn't even interested in the least). So, now he too can overclock a 6600 K to 4.5 GHz in under 40 seconds. He just turned seven (7) years old and has no notion of what overclocking is or possibly ever will be (couldn't care less), let alone any understanding of anything in the BIOS (who needs to know the meaning of the word "bus"?). That's a lot of credit to the enormous body of common sense he must be using in achieving this feat now isn't it? How / why then is this at all possible? Simply because this is about a modern CPU, not a gramophone of course. In the future this may simply be done with a couple vocal commands like "overclock 4.5" (who needs to know the unit of measure). Keyboards will be a thing of the past. That's it... move on Dear. We now have terrorism rampant everywhere and... Trump. This ain't the 80's no more.
As long as you use an old bios that supported non k over clocking which I do it works fine
i thinked intel stopped ovecolock non k ????
dude ever since the 80's people have been using blck/bus speed to overclock their CPU and RAM... It was only until the intel core cpu's came out that people started using core multipliers for overclocking. If you want to get the most out of your system WITHOUT fucking shit up, you use BLCK, not core multipliers. Just overclocking the core clock speed gives minor boosts in performance compared to overclocking everything else at the same time. You obviously need to do your homework and use more common sense and take your time when you're overclocking the bus speed, but it's definitely safer than just upping the core multiplier and leaving voltage on automatic.
I have to agree with ATIMarcos. I have a i5 6400 and mine runs at 4.6ghz no problem and I have yet to see anyone who can't get theirs to at least 4.5ghz if they set bios up correctly. IDK where they get the overclock results here but they are way low. I get the same benchmarks with my 6400 @4.6ghz as those I see for the 6600k @ 4.6ghz. You just have to make sure you get a motherboard that supported it at one point and dig up an old bios that still has it enabled. I have a cheap asrock z170 pro 4 and not only does it easily overclock my 6400 to 4.6ghz I also have no problem tweaking ram on that board. I currently have my 16gb g.skill v sticks running at 14-14-14-34 at 3000mhz @ 1.36v which really surprised me considering they are 16-16-16-36 2800mhz 1.2v sticks. Any time someone boldly states nope and thinks the baseclock will mess things up with skylake just pretend they never said anything since they clearly have no idea how skylake works and why it is possible with skylake and not the older gen.
wtf? a every motherboards company unlock the free blck oc for every 6000 skylake you can recha 4.5Ghz easy with some motherboard z170 with the unlock bios (basically, all) and arvid, yes, buy the 6400 with z170 motherboard and overclock via blck, is the fucking same processor with differente clocks.
Nope, the 6400 isn't an unlocked CPU, so you can't just increase the multiplier to match the 6600k. Good luck trying that with the baseclock and not screwing the entire system up.
Is the only difference the base clock speed? So I can base overclock (BCLK) the i5 6400 until they perform the same?
comments powered by Disqus