CPU really warm in idle but its cores and the cooler are cool

[Zybrion]

Hello,

Yesterday I finished my new build.
I have an I7-6700k on an z170 asus pro gaming aura installed.
For the CPU cooler I have a dark rock pro 3 with 2 fans.
For case fans I have 3 NoiseBlocker eLoop. 2 intake at the front, 1 pushes out the back.
I have the Corsair Air 540 case. No carpet and enough room for the air to escape properly.

Now to the problem:
The 2 fans at the dark rock pro are at a constant speed of 400 RPM. I set it so the case fans only turn on if the CPU runs hotter than 56°C.

With MSI afterburner I can read the temperatures. The real problem is that according to afterburner (and apparently the motherboard also) the idle temperature of the CPU is 50°C and it constantly rises to the 56°C line. Then my case-fans kick in and the temperature of the CPU drops to 50°C again in about 15-20 sec.

But the individual cores themselves are ALWAYS hovering in the 25-30°C range in idle.
And the cooler (dark rock pro 3) is cold to the touch. Even the heatpipes themselves.

So something isn't right. But I don't know what to do because the fans constantly turn on and off because of the (false?) temperature readings. Although the cores are cool.

Some sidenotes so nobody suggests them: I have removed the plastic cover from the cooler. I have enought but not too much good quality thermal paste installed. I reinstalled the cooler already and made 100% sure that it is correctly installed and is pressed hard enough against the CPU. This isn't my first pc.

TLDR: CPU runs hot in idle (50°C) although its individual cores are cool (25-30°C). The CPU temps always rise to 56°C then my custom set fans kick in, bring the temps down to 50°C again and the whole show begins again. All while the cores and the cooler are cool.

So the wierdest part is the CPU temps are at 50-56°C but the individual cores are at 25-30°C. But my fans go by the CPU temps so they always turn on and off...

Thank you for your help!

 

[synphul]

I'm not sure what cpu temps you're reading, package temp maybe at 50-56c? Core temps are what most folks watch and 25-30c sounds about right. The fans generally won't have to spin very fast on the dark rock pro 3. I'm using the same cooler, it will blow warmer air when under load but it has plenty of heatpipes and cooling fins to dissipate heat rather well.

It would help to know what program you're using, they don't all read from the same sensors. Some programs may for instance say they're displaying the 'package temp' and in reality the sensor it's reading is for the vrm or another component. It can also change from one model of motherboard to another. It sounds like whatever temp you're reading in the 50's C isn't the cpu temp at all but likely another component.

I'm not sure how you have your case fans set, ie fan curve and so on but it's possible they're reacting to other things like the vrm temps or inaccurate temp readings may be kicking the fans up. If the software tells the fans "speed up when the cpu reaches 55c" and the data field reading cpu temp is gathering temp data from elsewhere the fans won't know that. They're reacting to what the software is telling them and in reality the fans may be spinning faster/slower while the actual cores of the cpu aren't heating up that much.

I'm not running an i7 6700k, mine is an i5 4690k but I checked msi afterburner and cpu temps are reporting the same as I'm getting with hwinfo64 and realtemp. From what I understand on that board the fan control has the ability to use other temps besides cpu to control the fan curves. It's possible you have it set using a different temp to control the case fans rather than cpu temp.

In the user's manual for the motherboard, check section 2.7.5 which goes into the q-fan controls and shows how the chassis fans are set and selecting a temp value/source (ie, cpu, mainboard, vrm, pch etc). That would be my best guess without being able to see the settings in person, that your cha_fan headers (chassis fans) are set on a manual fan curve but reacting to another temp source other than cpu.

If you misplaced your manual it can be downloaded here.
https://www.asus.com/us/Motherboards/Z170-PRO-GAMING-AURA/HelpDesk_Manual/

 

[Zybrion]

I figured out that the 50-56°C I was refering to was the GPU and not the CPU. Kind of an embarassing mistake.
But my casefans still randomly spin up and turn off after a few seconds although the CPU temps are below 30°C and all my fan curves for the case fans are set to start at 50°C.
But I don't think you can help me with that :-(

So thank you very much for your answer!

 

[synphul]

Oh ok, well that does seem more normal for the gpu. We all make mistakes, at least it makes a bit more sense now. I'm not sure why the case fans are performing that way. It may be a matter of adjusting the fan curve until you get the desired results.