ASRock Z170 Extreme 6, is Non K Overclocking Still Possible?

Keith May



Back several months ago ASRock announced their SkyOC UEFI for Z170 chipset motherboards.  This feature allowed for overclocking non K sku Intel CPUs to be overclocked via the BCLK since the multiplier was hard locked.  During our overclocking tests with the i3-6100 on the MSI Z170a XPower Gaming motherboard we found that even after a significant overclock the i3 still fell a bit short of the i5 lineup.  This led me onto another thought process, what about the little i5-6400? It’s the entry level Skylake i5 with a 2.7ghz base frequency and a boost to 3.2ghz and coming in at $189.99 it’s only slightly more expensive than the top end i3, it only seemed like the logical choice and sweet spot for value when it comes to BCLK overclocking with Skylake.


While the overclocking went decently enough on the MSI Z170 XPower we really wanted to see how ASRock’s offerings fared in this scene since they were the big player in the beginning and really promoted the idea.  So we reached out to them and they were happy enough to send us over their Z170 Extreme 6 ($179.99 Newegg).  Now we are aware that Intel has put their foot down when it comes to BCLK overclocking and even ASRock has removed their SkyOC UEFI from their website, we began this conversation before that move was made.  And, if you know the right places to look all of these, no longer supported, UEFI are easy enough to find.  So after much deliberation we decided to proceed with this, the ASRock Z170 Extreme 6 and the overclocked i5 6400.

But we don’t want to jump straight to the results, we do want to take a tour around the motherboard and discuss some of its features.

Packaging and Motherboard

The box for the Z170 E6 definitely has curb and shelf appeal.  The front of the packaging is understated with a simple “Super Alloy” graphic surrounded by white lettering with the branding and model of the board as well as the supported features.  The back of the box interestingly enough is sending the message that this board is made for and catered to content creators showcasing full compatibility with both Nvidia Quadro and Radeon Firepro professional graphics cards.


Included inside the box are;

  • Motherboard
  • SLi Bridge Card (not that flimsy cable but matte black pcb connector)
  • Quick Installation Guide
  • Support CD
  • I/Shield
  • 4x Sata Cables
  • 1 screw for the M.2 socket

Now that the motherboard is out of the box and we’ve sorted the contents, it’s time to walk around the motherboard and see what all it has to offer.

Beginning with the rear I/O we have

  • PS/2 combination port
  • 6x USB 3.0 connections all supporting ESD Protection
  • Clear CMOS button
  • DVI, HDMI, Display Port connections
  • Intel RJ-45 LAN connection
  • USB 3.1 Type A and Type C connection
  • Purity Sound 3 7.1 channel featuring Realtek ALC1150 codec.

All of the rear I/O is covered by what has to be my favorite tacked on feature that came along with so many Z170 board, the I/O Shroud.   The shroud extends itself to the bottom of the motherboard covering the entire audio portion of the motherboard; upon inspection of the rear of the board the audio portion is separated from the rest of the motherboard to help eliminate noise interference.  Interestingly enough they added an extra motherboard mounting spot here.


Moving on to the PCIe slots they have positioned the x16 slot down one so that it allows for installation of much larger air coolers, like the Noctua NH-D15, and not have them interfere with the primary graphics card slot. Just below the x16 slot we have space for the Ultra M.2 slot with the moveable support for a M.2 SSD.  Moving down we have the second x16 (wired for x8) that supports Crossfire or SLi and allows for decent spacing between the two GPUs allowing them some breathing room.  The motherboard did include an additional x16 physical slot that is wired for x4 that would be useful for something like a PCIe SSD card.


As we move along the bottom expansion we have the COM port, two USB 2.0 connections, LED Readout, fan connector, and front panel connector. I want to pause for a second and direct attention to the two replaceable UEFI chips and the jumper just below them.  This board has dual UEFI, but not the typical “Backup UEFI” sort of way.  These are two fully independent UEFI’ much like our MSI XPower Gaming board was.  Unlike the XPower this has the jumper instead of a dip switch that means it’s a bit more cumbersome to switch between them, but not difficult with some light.



Since we decided to move forward with the BCLK overclocking discussion, despite Intel bringing down the hammer on it, we loaded the latest UEFI onto one chip and the SkyOC UEFI (found here) onto the other.

In terms of storage connections the SATA ports are appropriately separated into working groups with all 8 SATA 3 connections being available and next the bottom four are the SATA Express Ports.  If you use these SATA Express ports the motherboard disables the two adjacent SATA 3 ports.


Moving up the board to the CPU area we get a good look at the CPU power delivery and the memory layout.  Along the right hand side of the board we have the USB 3.0 front header, fan header, and 24-pin power connector.  On the top corner we get the convenient Power and Reset buttons on the board that come in handy when using an open air test bench or troubleshooting.  Just above those buttons we have two fan headers.


The four DDR4 DIMMS can handle up to a total capacity of 64gb.  Supports memory overclocking up to 3866+, with the caveat of anything past 3600mhz only being achievable when a single memory module is installed.  Our motherboard and i5 6400 had no problem handling our G.Skill Trident Z at its XMP speed of 3200mhz


The 12 phase power delivery surrounding the CPU socket is kept quite cool by the deceptively beefy heatsink and heatpipe combo.  I say deceptively beefy because while the top portion is very wide the base is narrow and most of it is basically a stand for the mushrooming top.  That’s not in itself a bad thing, but looking at the board one might think there is more heatsink than what there actually is.


UEFI and Overclocking


The UEFI included with this motherboard comes in two flavors, Easy and Advanced.  Easy mode is just that, very easy with most of the basic functions that most people would need access to laid out in a block format without the need to dig deeper.  The only option that goes into a deeper menu system in this layout is the System Browser where a graphical depiction of the motherboard and everything installed on the motherboard.


The Advanced UEFI is where the magic and fun really happen.  Upon entering this UEFI you’re greeted by the UEFI Version and current configuration of CPU and Memory.  Moving on to the OC Tweaker tab we find individual sections for CPU, DRAM, and Voltage configuration.  I do have to interject a complaint with this layout, it would be much easier to be able to adjust the CPU voltage from the CPU tab and the same with the Memory, but in the end it’s easy enough to go to one tab containing all voltages.  While we’re on the topic of voltages I can’t praise the LLC enough on this board, setting the LLC to Level 1 (a flat curve allowing no vdroop) the CPU maintains constant voltage to where you set it.  Set it to 1.21v and it does not fluctuate, set to 1.45v results in the same.


Overclocking and Results


For our top overclock we settled on 4.7ghz for the i5 6400 with a Bus Speed of 174.24mhz and 1.376v.  At this speed we were required to reduce the memory speed down to 2133mhz, but overall that was negligible for the massive clock rate increase that we got out of this 2.7ghz base clock, a full 2ghz Overclock.


Now the real test, was it worth it?  Since the i5 is highly regarded as the “gamers” cpu we did focus a bit more on the gaming side, but did compare for tangible benefits in workflow and power consumption.

Component Selection
CPU Intel Core i5-6400
Motherboard ASRock Z170 Extreme 6
Power Supply Bitfenix Fury 550g
HDD Crucial MX100
Storage Disk Seagate 4tb SSHD
Memory 16gb G.Skill Ripjaws Z DDR4 3200mhz
Monitor Nixeus VUE24A
Video Cards PNY Geforce GTX 980
Operating System Window 10 Pro 64bit


Kicking things off with Cinebench R15 we see the OpenGL score increase significantly showing the stock i5 6400 was heavily bottlenecking our GTX 980.  The cpu score scaled extremely well with the single core touching 200cb, which is no slouch at all.


Next we throw the i5 at R.O.G. Realbench to put it through a suite of practical application tests from GIMP, Luxmark, and Handbrake, then a combination to see how the i5 overclocking scales in real world situations.  Knocking 16 seconds off the Image Edition and a third the time off of encoding shows great gains.



Time to get into gaming, but first a quick synthetic most can relate to, 3DMark Firestrike.  The bit takeaway here is the stride that the i5 takes in the physics performance test.  Otherwise, we see the i5 wasn’t constraining the GTX 980 in the other two tests.


Now for some real games, DiRT Rally at 1080p Ultra Preset with 2xMSAA shows substantial gains to be had from overclocking, the new minimum is higher than the old average, and that’s something you can feel when playing the game.

Dirt Rally

Time for one known to be CPU intensive, Hitman: Absolution.  Run at 1080p Ultra Preset with 2xMSAA.  Here we see the overclocked i5’s minimum fps creep up the maximum stock i5’s rear.



Tome Raider 2013 (Last written article to use this cpu, retiring in favor of the new Rise of the Tomb Raider) was run at 1080p Ultimate Preset with FXAA.  This is just one of those games that don’t care about your CPU, we see both configurations running within margin of error of each other.

Tomb Raider

Tom Clancy’s The Division is another CPU loving game; we ran this one at 1080p on the Ultra Preset (disabled VSYNC).  Something to keep in mind on these results are the CPU FPS, this shows the load on the cpu throughout the test, so lower is better, and after we overclocked it we see the avg fps creep up but a huge drop on the cpu load allowing for the game to run much smoother.

The Division

Okay cool, so for the most part we see great gains to be had from overclocking the i5 6400, but what about power draw? Not quite as radical as you would think, even overclocked with a GTX 980 total system draw during Firestrike’s combined test topped at 313w, so not much to worry about there.

Power Draw


In The End

Ultimately this ASRock Extreme 6 was pleasant to work with. The UEFI was easy to navigate and offered plenty of features without becoming overwhelming (I’m looking at you XPower Gaming).  Offering up excellent overclocking potential even on a locked chip, if you’re willing to do a little digging and learn how to overclock the old way.  But with overclocking you’re still at the mercy of the silicon lottery. The selectable UEFI on the board is a great feature for this price range.  The one oddity that still stands out is the decision to locate the CPU fan headers just below the CPU socket instead of along the top.  The color scheme could be a bit off-putting to most people, but as usual beauty is in the eye of the beholder as it goes.  If you’re in the market for a midrange Z170 board with plenty of overclocking features in a user friendly format you really should be giving the ASRock Z170 Extreme 6 a serious consideration.


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