Hello all - I have an 8700k Delidded and OC'd to 5ghz at 1.35v.  It's 100% stable, I'm cooling it with a CLC240 which I picked up about a week ago.
 
I carefully mounted the radiator, ran the lines, all the connections are accurate, and I was pretty careful with mounting the heatsink on the CPU as well, it's not my first rodeo, I'm pretty confident it's mounted correctly, I also used Actic Silver 3 as well.
 
I have a push/pull setup, 120mm fans pushing air into the radiator through the front of my case with the supplied 120mm fans pulling it through as well.
 
My issue is the erratic nature of the temperatures, the fan profile when I set the CLC 240 to auto, spin up and down constantly, literally every refresh of the information in the flow control app because the CPU temperatures are spiking from 32c to 45c, and back to 31c and up to 44c, all random.  
 
I watch my CPU usage and it's pretty constant at 8 to 12% while I work, so it isn't spiking anything that would create this up and down issue.
 
Could there be something wrong with the cooler sensors?  I'm fairly happy with the cooler overall, but it's unfortunate not being able to have it auto manage the cooling due to the rampant up and down of the fans due to fluctuating temperatures.  
 
I have included a screenshot of the graphs associates with the flow control app showing the up and down temperatures, they swing constantly from 30c to 50c.
 
Thank you!
 
*Edit: Added a picture of the internals as well for added clarification.
 


 

Thank you for the reply. The odd part is, the coolest air should be being pulled through the front of the case, through the radiator into the case, then exhausted out the back and top. If I mount the radiator in the top of the case, the warmest air will be used to cool the radiator before exiting the case.

I can't imagine this isn't some sort of tuning issue in the software, I will attempt to remount my block before this evening, but I doubt that could play any effect in the disorder of the temperature. If anything a bad mount would just raise the temperatures.

I found slowing the pump down to about 2500 rpm and running a fan speed of 1500 dropped my I7 8700k about 5c the reason is like a  car radiator the longer the coolant is spent in the  radiator the cooler it will be coming out, by slowing the pump speed you are slowing the flow through the Rad. giving it more time to cool, but still keeping it fast enough to move the hot liquid away from the cpu, i would just play with the settings yourself to find a good balance for your setup.
 
 

Liftbikerun
Thank you for the reply. The odd part is, the coolest air should be being pulled through the front of the case, through the radiator into the case, then exhausted out the back and top. If I mount the radiator in the top of the case, the warmest air will be used to cool the radiator before exiting the case.

While this is true in theory, in practice it can vary depending on your setup and airflow. I have the 280 and Hybrid 120 at the top of my case, but I get enough cross flow where my case doesn't get filled with hot, stagnant air that would get sucked only upwards. For you though, I would say the theory is probably true since you have air-cooled GPUs and tighter space to work with. 
I'm not sure mounting the radiator on top would solve the issue. Erratic temps may be caused by trapped air bubbles which can be solved my mounting the radiator above the  CPU (Making the radiator the highest point in the loop and not the pump), but where you have your radiator is already higher so I wouldn't think this is an issue. Also most CLCs don't really suffer from this anyways.

I would say its probably software. Try using another monitoring software and check it against Flow Control to confirm or refute this hypothesis.