Have I failed in mounting my CPU cooler?

[Remote possibility]

Hi,

 

I have just built a second  new PC after a very long time of building none. It works but there is a slightly odd issue regarding the CPU fan and I am wondering if I have not used enough pressure. Its tight and I don't want to over tighten it but the CPU temp is hopping up and down when the PC is idling. The odd thing is that one I built with a Ryzen 3900 a month or so ago is fine.

 

The problem rig has a Ryzen 3600 cooled by a Noctua NH-U12S inside a Corsair carbide 200R. The case isn't great for cooling with a closed front but does have side and top vents. I placed an additional downdraught fan in the top in front of the CPU and the CPU cooler fan blows to the back of the case where there is a 120 mm exhaust. The Motherboard is a Gigabyte Aurus Elite and the top fan is plugged into CPU opt.

 

I first noticed the issue as the top fan keeps oscillating and when I look at the hardware monitor I see the CPU frequency is bouncing between 3590 and 3990 MHz with a corresponding bounce in the temperature between 36 and 48 degrees. and similar bounce in the CPU and CPU opt fan speeds. This is when the PC idle, doing nothing other than whatever Windows 10 is doing.

 

Is the a symptom of not enough pressure, not enough thermal paste or something else?

 

Thanks in advance

.

<edit>

 

Added a pic of the CPU fan profile.

[Allyxxx]

You may only need to adjust the fan curve. Idle temperature tends to fluctuate too much with that setting. If stress temps look to high it could be mounting.

[WoodenMarker]

It's difficult to overtighten with your bare hands. If the cooler can be tightened a bit more feel free to do so.