Stability issues with Z97E-ITX/ac mainbaord

Same problem here with precisely the same combination of board and CPU.

I'm still studying the Intel Datasheet for the Broadwell processors, but the reduced and configurable TDP processors like an i5-5675C (65W TDP standard Max, down to 37W if configured as such) are very interesting.

We don't have much experience with them in the forum, as they are not used by as many PC builders as other processors. In their datasheet, Intel has added more information and cautions about exceeding specific temperature and power limits than other processors, which may be related to your issue. Since you can reduce the instances of the issue by disabling Turbo, that is the first clue that temperature and power limits are likely the cause.

Please keep in mind that this processor is unlike other Intel processors in those respects. The default UEFI/BIOS settings for CPU power limits called for by Intel for this processor and likely implemented by ASRock, might be the cause of your issues. Knowing Intel's conservative nature, I would not be surprised.

Questions for both of you:

What CPU cooler are you using?

duck4, you said temperatures are fine, what are the idle temperatures? It is not well known that the maximum CPU temperature when the CPU is at idle/low clock speed is not the same as the maximum CPU temperature at the maximum CPU clock speed. It is much less.

I suggest increasing the default settings of these options in the OC Tweaker screen, at least as a test to see if that fixes your problem:

Short Duration Power Limit

Long Duration Power Limit

Long Duration Maintained

Primary Plane Current Limit

If you'd like to experiment with those options while in Windows, the Intel Extreme Tuning Utility (IXTU) program may allow you to do so. Depending upon how Intel has programmed IXTU, it might not let you change some or all of these options, that is common with IXTU. I don't have your CPU, so I don't know either way.

You can find that program here:

https://downloadcenter.intel.com/download/24075/Intel-Extreme-Tuning-Utility-Intel-XTU-

One thing I would try in your situation is setting your VCore to a fixed value (override not adaptive). Fire up CPUZ/hwmonitor etc and see what your CPU uses under full load and set your VCore to that in BIOS. Given that you seem to be having issues when the CPU is changing performance states I would lean toward the board not shifting the voltage quickly enough between low to high state changes. Obviously this is not a fix, and you will probably not want to run your CPU on a fixed VCore but it will help determine where the problem is coming from. If my suspicions are correct then it is likely that a BIOS update may be required to better handle performance state switching. If this is so then you will want to send a support ticket to ASRock tech support and link to this thread.

Edited by Xaltar - 24 Sep 2015 at 3:10am

duck4 wrote: Thank you, parsec for your response! I'm using the stock CPU cooler (with the thermal pad coming with it). Idle temperature is around 34~35 °C (with ambient temperature of about 21 °C) - seems okay to me. As for the power limit settings, I've tried changing these already, mostly because I was running out of ideas, what else to try. It seems no matter which values I choose, the crashes remain. If I set very low values, especially for the current limit, the CPU gets noticably slow, other than that, nothing much changes. Explicitly setting the power limit to 65 watts (which is the TDP of the CPU specified by Intel) does not seem to change anything over the BIOS default. I haven't tried going above that value.

I may be seeing your problem, the power limit set to 65W. TDP and processor power are really not the same thing. TDP is really the Thermal Design Power, the (minimum) amount of heat the CPU cooler must be able to dissipate to cool the processor properly. TDP and processor power usage, the latter being an average value, can seem to be the same, but aren't in many cases.

The transient, or short term burst power usage can be more than we ever see in monitoring programs. The power limit default setting on Intel mother boards meant for over clocking processors is set to 4095 Watts. That is the maximum value and overkill, but 65 Watts is very low.

Setting the power limit to a high value does not mean the processor will receive that much power, but only that much is available. Try setting the power limit to 500 Watts.

Also, what is the LLC, Load Line Calibration option set to in the UEFI? The default is 5, the lowest value. If you aren't familiar with LLC, higher settings (1 is the highest) prevent the VCore from drooping or dropping below the normal value, which tends to happen when the CPU power draw increases quickly.

Try setting LLC to 3, and increase the power limit to at least 200 Watts, and see if that helps.

Setting the power limit to the suggested 500 W did not help, the machine still crashes.