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Intel Core i5 6600K

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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

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Much newer manufacturing process 14 nm vs 32 nm A newer manufacturing process allows for a more powerful, yet cooler running processor
Much lower typical power consumption 73.94W vs 112.55W Around 35% lower typical power consumption
Higher clock speed 3.5 GHz vs 3.3 GHz More than 5% higher clock speed
Slightly higher turbo clock speed 3.9 GHz vs 3.7 GHz More than 5% higher turbo clock speed
More number of displays supported 3 vs 2 1 more number of displays supported
Newer Jul, 2015 vs Jan, 2011 Release date over 4 years later
Better turbo clock speed 1,150 MHz vs 1,100 MHz Around 5% better turbo clock speed
Better PassMark (Single core) score 2,148 vs 1,863 More than 15% better PassMark (Single core) score
Much lower annual home energy cost 21.92 $/year vs 41.29 $/year More than 45% lower annual home energy cost
Better PassMark score 8,012 vs 6,383 More than 25% better PassMark score
Significantly lower annual commercial energy cost 79.72 $/year vs 110.03 $/year Around 30% lower annual commercial energy cost
Front view of Intel Core i5 2500K

Reasons to consider the
Intel Core i5 2500K

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Much better performance per dollar 4.1 pt/$ vs 0.89 pt/$ More than 4.5x better performance per dollar
Much higher GPU clock speed 850 MHz vs 350 MHz Around 2.5x higher GPU clock speed
Significantly better performance per watt 6.79 pt/W vs 2.45 pt/W More than 2.8x better performance per watt
Higher Maximum operating temperature 72.6 °C vs 64 °C Around 15% higher Maximum operating temperature
Better overclocked clock speed (Air) 4.98 GHz vs 4.54 GHz Around 10% better overclocked clock speed (Air)
Better overclocked clock speed (Water) 4.88 GHz vs 4.57 GHz More than 5% better overclocked clock speed (Water)

Benchmarks Real world tests of Core i5 6600K vs 2500K

GeekBench 3 (Multi-core) Data courtesy Primate Labs

GeekBench 3 (Single core) Data courtesy Primate Labs

GeekBench 3 (AES single core) Data courtesy Primate Labs

Core i5 6600K
209.7 MB/s
Core i5 2500K
2,530,000 MB/s

Cinebench R10 32-Bit

Cinebench R10 32-Bit (Single Core)

PassMark Data courtesy Passmark

PassMark (Single Core)

Specifications Full list of technical specs


Core i5 6600K  vs
Clock speed 3.5 GHz 3.3 GHz
Turbo clock speed 3.9 GHz 3.7 GHz
Cores Quad core Quad core
Is unlocked Yes Yes


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 95W
Annual home energy cost 21.92 $/year 41.29 $/year
Annual commercial energy cost 79.72 $/year 110.03 $/year
Performance per watt 2.45 pt/W 6.79 pt/W
Typical power consumption 73.94W 112.55W


Architecture FSB DMI
Number of links 0 1
Transfer rate 8,000 MT/s 5,000 MT/s


Core i5 6600K  vs
Architecture x86-64 x86-64
Threads 4 4
L2 cache 1 MB 1 MB
L2 cache per core 0.25 MB/core 0.25 MB/core
L3 cache 6 MB 6 MB
L3 cache per core 1.5 MB/core 1.5 MB/core
Manufacture process 14 nm 32 nm
Max CPUs 1 1
Operating temperature Unknown - 64°C 5 - 72.6°C


Overclocked clock speed 4.54 GHz 4.98 GHz
Overclocked clock speed (Water) 4.57 GHz 4.88 GHz
Overclocked clock speed (Air) 4.54 GHz 4.98 GHz

integrated graphics

Label Intel® HD Graphics 530 Intel® HD Graphics 3000
Number of displays supported 3 2
GPU clock speed 350 MHz 850 MHz
Turbo clock speed 1,150 MHz 1,100 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 21,333.32 MB/s
Maximum memory size 65,536 MB 32,768 MB
Intel Core i5 6600K
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Intel Core i5 2500K
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Showing 25 comments.
Did the same for my brother in ended up being a side grade compared to my 2500K which isn't even clocked.
Of course, there will be improvements in performance with an upgrade. But for myself that is not the issue on when to upgrade. It is when I cannot effectively perform (process) what I want or need to do in a timely manner or have a hardware failure. And that folks means new software (games, graphics, etc) that requires additional processing power. As of 2016, there is nothing to date that I throw at my 2500k Sandy Bridge that it cannot handle.
I know what you mean, im doing the same, not really because the 2500k sucks, it doesnt, in fact, it's definitely one of the best cpu i've ever bought, it offers so much value and I'd probably still use it for years... Sadly i need to upgrade my mother board because i damaged my current one while moving my computer, i didn't remove the relatively heavy air cooler that i was using, i didin't had thermal paste with me at the time to reapply it :( I wanted just to buy a sandy bridge compatible mobo but it's kinda coimplicated here where i live, i couldn't find a used one for sale and shops are still selling new ones at full price, i mean, i'm better off just upgrading, and a new mobo requires a new cpu as well.
sounds more like a sidegrade then an upgrade
What kind of difference? A 5 seconds faster boot process and other minimum , uninteresting and in everyday life for 98% of PC users uninteresting and unimportant differences ? Yes madness , but otherwise spend much money so that one in benchmarks has more points , laughable ... My buddy has changed from the i7-2600K to i5-6600k and regretted it every day , not because of the i5 is bad but because it is not worth the money ... I use my i5 2500k any case until it makes sense REALLY
Night and day difference with the ssd. Worth every penny!
oki :D thats nice, wanted to buy new CPU along with new GPU...but screw it. Gonna finally upgrade to SSD instead!
Your 2500k is more than good enough gaming. Newer video cards are pci-e 3.0 but they don't utilize them fully yet so no big deal there. Pci-e 3.0 would likely be important if you used pci-e ssds or something that can actually take advantage of it.
so If I have no idea what pci-e 3 is...and really just want it for gaming...IM still good with my trusty 2500k? I remember reading its awesome CPU.
I built a pc with 2500k 4 years ago. Only OC to 4.7. First upgrade was a 500gb SSD this made it very quick. Put in 16gb ram Then upgraded the GPU to a GTX 980 TI Seahawk (built in water cooler) Added a 144mhz monitor. I can play any game at max settings. I have looked and read so much about the skylark 6600k and I have no reason to upgrade yet. When I do I know it will have to be Motherboard, ram and CPU. But as this cpu seems to still keep up with skylarks I spent the money on GPU instead.
Yeah I remember the day I bought an e8400. I wondered then how long it would be until AMD were competitive again. The value chips are there but they lag on grunt...
Only valid reason i could think about why anyone would upgrade from a 2nd gen i5/i7 to a 6th is the chipset the new motherboards have. I don't remember exactly the details now, but i think the Z170 brings along some good stuff with it ( mainly DDR4 support ) Still, it is sad to see how little of a upgrade is the CPU. Personally, i blame the lack of competition from AMD.
I had both types of 8800 - so good at the time. Crysis could still make em weep though ...
You will be so happy with that. I went from an athlon 3200 to an e8400 and then a 2500k :-)
Yep, every year I've wondered but nothing seems worth it. Mine clocked to 4.8 the day I got it with about 3 clicks in the Asrock bios. Been that way every since. This year I looked hard, realised there is still no point and this week I scored a cheap extra 2500k box 2nd hand to upgrade my lounge room :-). Typing on it now. All the support systems have been surpassed of course but a 2500k with a pretty mild and completely stable 4.8 clock remains useful. Kind of sad that CPUs have stagnated so much.
I plan to upgrade to 6600K since I still use the Athlon II X2 250 which is quite old. So yeah, this isn't a bad choice unless you just one generation behind.
My experience is much the same as yours. I built mine 4 years ago as a Crysis box with the i5-2500k and a single 8800GT. Still cooking along at benchmarks too high for the expense of upgrading. I just need to put on a good air cooler as the stock cooler is showing its age. Only tweak has been bigger drives and SSD boot. Rock solid performer over 4 years.
it depends really. do you want things like pci-e 3? if you are just a gamer then i would say no, just oc that bad boy ...
Built a 2500k system 4 years ago withone of the early z68 motherboards and a samsung 830 256gb SSD and its been running OCd @4.7 basically 24/7 with a Coolermaster that was slightly too tall to use the side panel on a old stock small ATX tower I stripped a previous AMD quad core black edition I used for a year or two prior and I have to say the 2500K build has been a real pleasure to work with, ive used it for everything from gaming with the OC version of the early 7850 wich repllaced a HD4890, Ive been just as pleased by the lighter cooler running GPU, I dont think ive ever heard this builds fans ever get loud enough to notice in the entire 4 yrs I used it. I honestly expect to replace with current gen hardware from each manufacture for my next build but im finding it difficult to make the upgade just yet because the older sandybridge still does a fine job. However Ive definitely become a big fan of the unlocked intel CPUs and the few years using the samsung SSD has made working on relatives PCs much more frustrating after getting used to the snappier performance, a standard 2 TB WD green has been a good media share drive. I look forward to the next build and hope It holds up like the 2500K has, There was a time when 4 yr old hardware in a gaming machine was like being in reverse, but I think the old Sandybridge build still has everything I need for now and I would say there are alot of owners who feel the same way. The whole experience makes me look forward to building another one someday even more.
I'm upgrading from a 2500K to 6600K, but simply because Intel forces me to with the slightly changing sockets with nearly every release... -_-
So upgrading from the 2500k to the 6600k isn't worth it?
overall it's like 30 to 40%
Ikr why would anyone upgrade, 4 gens later, 15% boost on single thread. And power consumption isn't lower either.
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