Skylake Non-K Overclocking Performance Tests

Few days ago the overclocker DHENZJHEN uncovered the Skylake Non-K overclocking capabilities of the Supermicro H170 mainboard and set serveral new top scores on with an overclocked Intel Core i3 6320 at about 5 GHz. He also found out that the overclocking limit was only caused by the BIOS itself. There was no special hardmod needed to overclock the Core i3 6320 which usually has a stock clock of 3900 MHz.

Unlike K-CPUs which can be overclocked using the multiplier, Skylake Non-K overclocking can only be done using the BCLK. Pre-Skylake CPUs such as Haswell or Devils Canyon could only be overclocked by about 3-5% using the BCLK because the BCLK was still tied to the DMI and the PCIe.

Update: Find all non-K BIOS in this Post: !

Skylake Non-K Overclocking

Skylake Non-K Overclocking Basics

slide-3However, for Skylake CPUs, BCLK and PCIe have a dedicated reference clock which always stays at 100 MHz – no matter how you change the BCLK. In other words: You can push the BCLK without worrying about other components.

This gives great overclocking opportunities in theory. Some overclockers at HWBOT came across a BCLK wall of 102.8 MHz after they tried the new i3-6320 in the Intel XTU Benchmark. It was quite obvious that it was a natural wall so people started to try to bypass this limit.

So far ASUS and ASRock showed some pretty impressive results on liquid nitrogen cooled setups. ASUS published scores today with a LN2-cooled i3-6300 clocked to 5800 MHz for multithreaded benchmarks (elmor i3-6300 @5800 MHz Cinebench).

Apart from the impressive extreme overclocking results, this is amazing in many ways. Intel stopped the “free overclocking” with Sandy Bridge by introducing the K-CPUs. Skylake Non-K overclocking is a Throwback-Thursday for the whole overclocking community and also great for 24/7 Overclockers to save a lot of money.

Luckily I have quite good access to hardware (thanks Caseking!) and just grabbed some CPUs from the warehouse to do some testing.

CPU NameCore CountStock ClockTurbo ClockHyperthreadingL3-CachePrice
Pentium G4400T22900 MHz-No3 MB70 €
Core i3-632023900 MHz-Yes4 MB160 €
Core i5-640042700 MHz3300 MHzNo6 MB185 €
Core i5-6600K43500 MHz3900 MHzNo6 MB260 €
Core i7-6700K44000 MHz4200 MHzYes8 MB400 €

My setup:


I used the ASRock Z170 OC Formula to test the CPUs. All you need is a special BIOS which you can download here:



  • Enter the BIOS and go to the OC Tweaker – DRAM Configuration.
  • Load the XMP Profile to adjust your memory correctly
  • Adjust the BCLK to the level you need (see picture above with i5-6400)
  • Adjust the DRAM Frequency to the correct level. I had to stay below 2800 MHz on the memory to achieve high BCLK clocks
  • Go to: OC Tweaker – Voltage configuration
  • Set 1.350 fixed core voltage. Leave everything else on auto.

My i5-6400 turned out to be great and I could even run 4725 MHz on 1.375 Volt which equals an incredible overclocking of 75 %.


The only problem about the “special BIOS” is the fact that you can’t read out the core temperature. No matter which tool you use, you will always see 100°C. However, after clocking a lot of 6700K CPUs I can tell that anything below 1,40 Volt is fine with proper cooling like the X61 Kraken. Even cheap and weaker air coolers can handle these CPUs at up to 1,40 Volt. Especially the i3 and Pentiums CPUs only produce a small amount of heat.


I didn’t have much time so only tested Prime95 quickly but as you can see 170 BCLK was no problem for a quick test. According to the Kraken Software there was close to no heat so you can be sure that these values are safe (clock and temperature-wise).

Skylake Non-K Overclocking: Cinebench R15

I did some quick Cinebench testing because you can compare multi-core and single-core performance pretty well with other CPUs. For Skylake CPUs I kept the memory between 2600 and 2800 MHz depending on the memory divider and BCLK.


The single-core performance is pretty important for applications and games which don’t scale well with multithreading. The 70 € Pentium G4400T is doing pretty well overclocked to about 40 % and even matches the i7-4790K. Both, i3-6320 and i5-6400 beat the high-end 6700K when it comes to single-core-performance.



Multithreading is the real deal and you can see that the Pentium G4400T has no chance against the other CPUs – even overclocked. However, the Pentium comes close to the i3-4370 which costs twice as much as the Pentium. The i5-6400 performs amazing considering the price of only 185 €. Overclocked by 75 % you can come close to the i7-4790 which costs over 300 €. All in all – amazing!


Skylake Non-K Overclocking Conclusion

It’s surprisingly easy to overclock these CPUs on the ASRock board. ASRock did an amazing job with the new BIOS. There is nothing you have to take care about apart from Base-Clock, Core-Voltage and Memory-Clock. I could reach the 75 % OC within 10 minutes without any special settings or CPU-binning.

It’s also pretty obvious that the CPU clock is not limited by the BCLK. 170 MHz was no problem using the i5-6400 whereas I could not even reach 120 MHz using the i3-6320. So I advice to get cheap CPUs with low CPU multi and push the BCLK.

Of course it makes no sense to get an ASRock Z170 OC Formula in combination with a Pentium G4400T. However, it’s just a matter of time until we will see unlocked BIOS for cheap Z170 or even H170 boards. In the end this is still the best OC-News since Sandy-Bridge considering the fact that I could gain +75% OC which results in +52% performance.


Update: Find all non-K BIOS in this Post: !


If you have any questions, don’t hesitate to ask in the forums:

Overclocking.Guide Forums


ASUS Maximus VIII Gene Non-K OC BIOS
7.90 MB | 2530 downloads
ASUS Maximus VIII Hero Non-K OC BIOS
8.04 MB | 4518 downloads
ASUS Maximus VIII Impact Non-K OC BIOS
7.89 MB | 2451 downloads
8.00 MB | 10935 downloads
ASUS Z170-Deluxe Non-K OC BIOS
8.08 MB | 2064 downloads
8.00 MB | 2778 downloads



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  • I would be interested to know how locked i7 – 6700 with BCLK 170Mhz in multithread score would be.
    Anyway, probably no point to buy K version now of i7 6700.

  • Luumi

    Well Roman for normal user at this point it’s easy to just tell to test voltage at stock as probe stops working after 103 baseclock.

  • Hello Roman,
    very nice article. The performance in Cinebench of core i5 OCED is very similar as OCed FX-8350! Wow. If these unlock BIOS will be aviable to download for people, after Skylake platfrom is best since Lynfield/Bloomfiled days :)Do u know what exactly is in this BIOS? Its some microcode for unlock BCLK? Or some more details?Thx 🙂

  • spajdr

    I find it strange that only top mobos have this bios now, shouldn’t be this mainly for cheaper mobos first?

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  • Tzk

    The performance of the i3 6100 would be interesting too. This i3 is the only real alternative to the i5 6400.
    i3 6300 and 6320 are way to expensive for the performance 🙁

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  • Asrock released earlier today Skylake Overclock BIOS for non-K CPUs for all of their Z170 mobos 🙂

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  • Mikael

    In all those non-k overclocking guides is this line “Avoid high memory clocks. Everything around 2600 MHz will be fine.”. Higher RAM clocks cause instability or what?

    • der8auer

      Some CPUs can’t handle the high memory clock in combination with high BCLK so the system won’t boot with the wrong setting

  • Jordan

    This is probably the dumbest question of all time, but will the incorrect temperature readouts cause motherboard fan control to run fans at full speed? (Or whatever the motherboard’s critical temperature speed might be?)

  • Edward

    Do you think Intel have any plans on patching this in any way ? iam building a new pc and just found this out and would grab a 6400 non-k chip

    But if you think they can stop this i would probs just grab a 6600k

    • der8auer

      Intel doesn’t really care about this so far. I also talked to some friends inside the hardware scene and they also told me that intel doesn’t really care about non-K oc.

  • Kaleb

    Would i be able to get an i3 6100 up to 5ghz with a Asus Z170M-PLUS Motherboard at 1.4 core voltage??

    • der8auer

      Most CPUs have a limit around 4.5 – 4.7 GHz on normal cooling.

    • Wintrymix

      I have my i3 6100 at 4.625 GHZ at 3.50v. Very stable through several gaming sessions and a couple Cinebench runs. I’m cooling it with air via a CoolerMaster TX4. I can hear the fan spin up a bit during the benchmark, but not excessively.

      Single Core Cinebench R15 score – 193. ( Just wow. This chip….)
      Multi Core Cinebench R15 score – 492. (Very respectable)

      Just for some perspective, an i7 4790K at stock speeds scores around 180 on the single core Cinebench R15 test. This little i3 has insane potential.

  • Bosanjero

    Thanks to OCguide-Team especially to der8auer.
    I have OC successfully 6500 @ 4.8, unfortunately ASUS Pro Gaming Bios1301 Vcore is not easy adjustable so I left it on auto, Vcore climbed to 1.4V after BCLK150 even 1.5V
    Want to Change Mobo,need better BCLK-Bios support by Manufacturer and possibility more Vcore options. May be ASROCK Extreme4
    What is your opinion ?
    Best Regards

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  • Roberto

    How is Intel closing the BLCK overclock… via a BIOS update? If so, can’t enthusiasts just not update the BIOS on a compatible Asrock or Asus board?


    • Ryan P

      This. I think it may depend upon how the microcode update is delivered. I believe the update can be delivered via Windows update, essentially without the user knowing. I’d be interested to hear @der8auer’s opinion on the subject.

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  • Roberto

    “In an interview with PC World, a company spokesperson stated: “Intel regularly issues updates for our processors which our partners voluntarily incorporate into their BIOS,” an Intel spokesman said. “The latest update provided to partners includes, among other things, code that aligns with the position that we do not recommend overclocking processors that have not been designed to do so. Additionally, Intel does not warranty the operation of the processor beyond its specifications.” So how does this micro-code update work? For starters, it will work only if you want it to. If your motherboard currently supports overclocking, then it will continue to do so, until you update its BIOS. Intel will push the new micro-code to its motherboard partners, who in turn will deploy it on their latest production batches, and to their customers through DIY BIOS updates.”

    Hope this is the case!

  • Roberto

    Temp monitoring is working on my Asrock Fatality Z170 K4! I’ll add a temp probe to the CPU tomorrow to verify but seems accurate. Glad I’m not “stuck” with 100c

    1.3v i5 6400 @ 4.2Ghz = 55c under load (good air cooling) see screenshot

  • Alex

    Wouldn’t it be possible to overclock for example a Xeon E3-1230 v5 using an ASRock Fatal1ty E3V5 Performance Gaming/OC on bios version 1.10 as well?

    According to the release notes they have removed the Sky OC feature for the latest bios update meaning that it must have existed before:

    Also this motherboard supports the Xeon so it should be overclockable on it.
    That would be a very interesting combo price/performance wise. It would be nice if you could try that.

  • kithylin

    Has the temperature monitoring problem been resolved by now? Is this custom bios able to monitor temps on all cpu’s now?

  • roxta

    I dont get it, My Bios (newest Version for ASUS Z170-A) actually has a field for changing BCLK. Does this mean i dont have to flash my Bios in order to OC? Is this Feature allready in the Standard BIOS? Because i tried to push my BCLK up bit by bit but i cant go any higher then 103Mhz (It just wont boot if i do so). Does this mean that the “unlocked” Bios i can download from here will just disable this Wall?

    btw i use a i5-6600 on 1,3V

  • So is the Core i7-6700k the best CPU for overclocking?

  • enterprise24

    Can a cheap Z170 M/B such as Asrock Z170 Pro4 push base clock to 200Mhz or more ?
    I think about getting i5-6400 but fear that x27 multiplier and cheap Z170 M/B will not OC much.

    • enterprise24

      Update : I already order i5-6500 (fear that a cheap M/B will not push bclk pass 170Mhz. I see every non K OC stuck at bclk around 170Mhz except with high end M/B) and G.Skill Ripjaws V 2x8GB 3000Mhz.
      Still decide on M/B though.

  • shatter dabbed

    I have asrock z170 extreme 4 w i5 6400 and it o/c very very well I. 1.3 v stable at 4.2 60c temp w noctua cpu cooler. also tried 4.5 and that was stable as well temps 65c load 30s idle. the asrock windows utility does read the temp correctly. I have thermal throttling disabled just in case. also had to disable c state in bios or pc would lock if put in sleep mode. and my memory runs at rated speed 3000 g skills trident….very good article over locking non k cpu is legit…

  • Daniel S

    Does anyone have experience with the Asus Z170M-PLUS and the i5 6400? Can the chip be overclocked to 4.6ghz with this board and if so, would it be stable for gaming?

  • Cecropia11

    I have a i7-4720HQ processor in a ASUS N550JX ROG notebook, and it is capable of being over clocked to a maximum of 3.8, 3.7, 3.6, 3.6 GHz I run mine at 3.8, 3.7, 3.5, 3.5 to keep it cooler under full load, stock it runs at 3.6, 3.5, 3.4, 3.4 GHz. You can do this in the Intel Extreme Tuning program. I am not sure what the maximum of the i7-6700HQ is, but even stock, the i7-4720HQ is faster… PERIOD

  • Cecropia11

    Also under full load I can keep it under 90C, max for the i7-4720HQ is 100C.

  • Marco

    I have the current oc bios from your side drauf and my i5-6500 is according to cpu-z at 4.5 GHz. In the cinebench I get but only a score of 556 and am far below your. What can be the reason?


  • Neil Mathieson

    If I own a Gigabyte Z170 Mainboard that isn’t listed here, can I use another mainboard’s BIOS to enable an OC on my i3-6100 CPU?
    Mine is a GigabyteZ170X-Gaming 6

    Thanks for your help.

  • PiotrLenarczyk

    HT in my personal opinion is rarely used in typical applications in OS. In my tests the size of L3 is more important for programming issues ( with disabled HT, there were better of few % timings for CPU, and CPU + GPU basic mathematical operations programs ), but check it personnally for your hardware. I use Dell Inspiron 7746 with single non-CD drive SSD hardware platform.

  • Mic

    Asrock ITX z170 + 6400 @160MHz, 1.3v Vcore. 2720MHz RAM, stable as hell. Used an AeroCool 3 pipe air cooler, Prime95 8K test climbed up to 70C with min case fan speed.
    I was trying to tune up a little bit, but any change would cause a system crash. When I say system crash, it means I can’t see anything on screen, and computer would lit up for half sec and turned off, and circle that until I turn off the PSU and try to boot for a couple of times. Anyone else met similar issues? Any ideas or suggestions?
    P.s. I have a very good score with Cinebench and cpu-z cpu bench, 580 and 90% of 6700k respectively. I want to climb from 4.3GHz to 4.6GHz @170MHz.

    • Mic

      cpu-z was 80% of 6700k

      I have disabled some auto options in bios, change them to fixed values, now I can use 165MHz @4.45GHz
      I thought it might be just a little improvement, and I was wrong. Cinebench has 734, way better than 580 @4.32GHz
      cpu-z also benches a 87% of 6700k performance. I used 1.325v + 1600~ish Mhz, p95 8k test goes up to 77C, still much better than my 3770k @4.5G with a 90C p95 8k test. Love it. I will forget 170MHz OC and still with current settings. These numbers above are just references and I am not responsible if you can not use my configurations to achieve the same performance.

      Thanks again for this post and the website.

  • Tina

    Just the first Z270 boards are out and I did ask Gigabyte support about the GA-Z270-HP3P:
    “…I wonder if I would have the possibility to ‘overclock’ Intel non-K CPUs by changing the BCLK frequency?
    Or is this feature locked like on the Z170 mainboards, and I would have to use a third party BIOS?

    They answered:

    The board allow to adjust BCLK with non-K CPU. ”

    So I did order one and a i5 7400 and will let you know 😉

    • Tina

      No joy at all:
      I got today:
      Gigabyte Z270 HD3P, 2x8GB Cosair 3200, Pentium G4560
      the BCLK is fully locked i n the BIOS, only 100MHz possible. Not even 1MHz higher or lower…
      Gigabyte is IMHO therefore as “professional” as ASUS. They both let me down now. Giga see above and ASUS stopped support for their 3 year old MB (“buy a new one”).

      Now sending all back and waiting for a Asrock….

      • I really do appreciate your testing og non-k kerby overclocking. Some of these cheap 4 thread CPU’s, with overclocking, would be amazing.

        I’m looking to do the exsact same ting.

        • Tina

          Just got an answer of ASRock Tech Support:
          “According to Intel policy, only Intel k-series CPU and Z-series chipset are able to support overclocking.
          The O.C. mode is locked by Intel Microcode, …”

          My Question was if the ASRock Z270 mainboards would allow non-K KabyLakes to be overclocked.

          So as far as I can see atm the only possibility to overclock non-K’s a Z170 with an old BIOS (older microcode). How I understand once you did a BIOS update with new microcodes or get one with newer microcodes there is no easy way to rollback to an old BIOS version. I did read that you could try to use the intel fpt program (of the Intel MEI package), but I cannot confirm that. I still run a AMD 1090T on a 870 at this time :/

          I do not know now where to go next, as the Z270 is most possible a dead end presently to OC a non-K.

          • Tina

            Gigabyte did finally answer too, to the subject if the GA-Z270 would allow to OC non-K Kaby Lakes above 105MHz BCLK:
            “…Thank you for emailing GIGABYTE.
            We are delighted with your interest in our products.
            Our team did send a screenshot:[edit: removed BIOS screenshot of G4560 OCed to 102MHz BCLK]
            Z270-HD3P doesn’t has Turbo B-Clock IC onboard like Z270X-Gaming 7 so BCLK OC above ~102…105 MHz is impossible…”

            Z270 non-K overclocking is dead for the moment 🙁

  • If I own a Gigabyte Z170 Mainboard that isn’t listed here, can I use another mainboard’s BIOS to enable an OC on my i3-6100 CPU?
    Mine is a GigabyteZ170X-Gaming 6

    Thanks for your help.
    Further details available at

  • I have the i7 6700k and despite getting a corsair h115i cpu cooler and a motherboard (Asus a170-a) with loads of overclocking options….I still haven’t found the guts to try overclocking it 🙁

    Might give it ago this weekend after reading this.

    • letmecomment

      Check youtube videos on how to do it, basically in 2017 it’s almost 100% of chances you won’t screw up and loose your hardware

      Just start from a low vcore (1,25+) and keep your temps low, good luck

  • Do you think it’s worth upgrading this with Kaby Lake or is it too similar in performance

    • If you’re sitting with a Skylake then gains will be fairly minimal. I upgraded from a 2500K to 7700K and felt a massive difference.

      Previously I was running a 2500k with Gigabyte GTX 1080 Gaming G1 for about 3 months before upgrading to 7700K. So glad I did!

  • Higher RAM clocks cause instability or what? Is this custom bios able to monitor temps on all cpu’s now?

  • NB

    What is the best motherboard currently available that can overclock an i5-6400? I just picked up a refurbished HP 560-p015hvr with Radeon RX-480 4GB GDDR5 and I’m looking to max it out the CPU without breaking the bank. Also grabbed a EVGA 450w PSU to replace the included 300w ATX. Suggestions for a replacement MB that supports OC’ing the i5-6400? Thanks

    • Zen

      Personally this is what i would go with. It’s an ASrock which long ago was frowned upon by the likes of mainstreamers like asus and MSI, but now they are highly competitive. Their quality is really good, and you get a lot features for less. and you dont want to pair a super high end board with a low end non k chip, so this is a midrange board $130 range which is a good pairing for an i5 -6400.

      I have it myself after seeing it getting an award on toms hardware. Board is amazing, early bios’es are perfectly stable no issues. That board has a toggle so it has 2 bios, you dont want to flash to the latest bios, that will have intl microcode locking the bclk field. So flash to one of the earlier revs and just set volts to 1.275 and crank up the bclk. im running at 4.2ghz, stable cpu, temps stay in the 50s during stress test with noctua air cooler. and memory i have all the way to 3,000 which is good considering overclocking the cpu causes stress on the memory controller

  • suleymanspadre

    Is Windows 10 microcode an issue? I am running a Hyper 212X. Will that be sufficient?

  • Can you also post about the Intel Core-X series CPUs Overclocking Performance. Thanks

  • binhdt

    My MB is Asus Z170 Pro Gaming Aura, and i’ve Download “ASUS Z170 Pro Gaming Non-K OC BIOS”…..
    But when i try to Flash >>>> It says: “This is not a proper BIOS”, can anyone help me?

    i’m Using Core i7 6700 Non-K…. can i still OC it ??

  • is there any method of overclocking with less power consumption

  • So is the Core i7-6700k the best CPU for overclocking?

  • awesome…much appriciated.

  • much needed article…will use the things for my personal tasks

  • I kept the memory between 2600 and 2800 MHz depending on the memory divider and BCLK.

  • Thanks for this awesome guide. I have recently bought the Core i7 8700k processor for my gaming PC will Overclock.

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