Underclock i7-6700k to use in a Deskmini 110

The 6700k should work fine at stock settings so long as you use a decent cooler. As the K class CPUs do not come with a boxed cooler you will have to source a 3rd party cooler, preferably something with heatpipes that will fit in Deskmini enclosure. 

qeshi wrote: Hi! I already have an Intel Core i7-6700K Skylake Processor and want to make my computer more portable by putting it into a Deskmini 110. Since the motherboard in the Deskini the H110M-STX has a H110 chipset it will not let you overclock your CPU. This got me a bit worried, they seem to have limited the options to set the voltage and clock speed for the CPU in the bios. So I'm wondering if the H110M-STX bios will let me underclock / undervolt my CPU, or are these bios options also limited? I tried to find an answer in Deskmini user manual: http://www.asrock.com/support/support.asp?Model=DeskMini%20110%20Series&cat=Manual There is something called a Long Duration Power Limit and Short Duration Power Limit. Would it be possible to set these options to 65 watts to get a stable system for a i7-6700k? Thanks in advance to anyone that can help me out with this!

I have a DeskMini 110W PC, so I can give you some tips about using it. But I don't use it with an i7-6700K, I have an i3-6100 processor.

You are right about the limited options in the UEFI/BIOS for setting processor options like VCore, core multipliers, Turbo, and even the BCLK. They are not available with my i3-6100 installed. So I cannot be 100% certain if any of them will appear when a 'K' processor is installed in the board. My guess is they would not be available, with the potential exception of the Turbo option, since some of the standard supported processors for this PC have the Turbo feature, such as the non-K i7-6700.

I understand your concern, particularly since the Skylake i7-6700K is known to have surprisingly high stock VIDs for stock core multipliers. That is, about 1.4V, which is way more than necessary. We don't see that with the i5-6600K. I assume Intel does that with the i7-6700K due to its relatively high base clock of 4.0GHz. The VID does not automatically translate into the equivalent VCore, but if you can't adjust the VCore, you're stuck. Did you notice the high VIDs with your 6700K in, I assume, a Z170 board?

The main situation you may need to deal with is the CPU temperature. But it will only be a "problem" if you would be nervous (as I would be) seeing idle CPU temperatures at 35C - 45C. That of course is not really an issue at all, those temperatures are well below the ~100C throttling temperature of a Skylake processor. Plus any fear of those temperatures is simply being conditioned by low CPU temperatures caused by using after market CPU coolers.

Which brings us to the next situation, the limited selection of CPU coolers you can use that will fit in the DeskMini 110 PC case. You don't have a stock Intel CPU cooler provided with your 6700K, although any intel socket 115x CPU cooler can be used in the DeskMini Mini-STX board.

I have several stock Intel 115x CPU coolers provided with other Intel K processors, and used one of them with my DeskMini 110W initially. I was not happy with its performance, although it was not inadequate for the job. I'm just fixated on low CPU temperatures. I bought a Thermaltake Slim X3 CPU Cooler, which fits in the mini-STX board fine. I was even able to replace its 80mm x 15mm fan with an 80mm x 25mm fan, which fit in the DeskMini case fine. The maximum height of the CPU cooler is 42mm IIRC. But the width of the CPU cooler is also restricted, so you must be careful not to ignore the width. The Thermaltake Slim X3 CPU Cooler's dimensions are 99mm x 91mm x 36mm (stock fan.) Other options for CPU coolers are the Cryorig C7, and other small CPU coolers.

Xaltar's comments about the chipset temperature and using an M.2 SSD are exactly what I thought would be true. I've used two different M.2 SSDs in that board, and I was surprised to discover the temperatures of the chipset and the M.2 SSDs were not as bad as I thought. The fan on the CPU cooler makes a big difference. I had better chipset and M.2 SSD temperatures using the Thermaltake CPU cooler. I put a small heatsink on the chipset, no more than 10mm in height, which just barely fits under an M.2 SSD. I also have a small heat sink on the M.2 SSD's controller.

The Long and Short Term Duration Power Limit options in the UEFI are really more useful when over clocking. They apply to Turbo boost power, not the standard power usage of a processor. You'll find the default settings (Auto values) of those options to be much higher than the TDP value you mentioned. The processor TDP value is really the amount of heat that must be dissipated under maximum load, and is not the same as the Power limits.

Xaltar's suggestion of using the Windows Power Plan processor power state percentage is what you really should use to underclock your CPU. Also using all the processor C State options in the UEFI/BIOS will reduce the CPU speed under low load conditions.

Other possibilities to adjust a 'K' processor's speed and VCore would be to install the Intel Extreme Tuning Utility (IXTU), since it might provide you with more options to adjust than the UEFI/BIOS provides. Yes, it is intended for over clocking, but it might give you access to the core multipliers, etc, and allow you to set them below their standard values.

Also, there is a program called ThrottleStop, that was created by its author to allow setting processor options on laptop PCs that are normally not available in their BIOS. I have not yet tried it with my DeskMini 110W, but it might allow you to do what you'd like to do.

I would go with something more like this:

Hi,

So did you build the PC ? Is it working well ?

What about putting an i5 6600K ?

I am also looking for references to replace the stock intel ventirad by a more efficient solution.

Thanks for your help

Thank you Parsec for you extensive answer and insights.

I will stick with a non K version probably with the i7 6700.

The CPU coolers you gave doesn't seemed easily available in Europe but I will keep looking (if it worth changing Intel stock one)

Excited to build this thing :)