So, restart the system, do not open any programs except for whatever program you are using to monitor temps. I recommend using HWinfo or CoreTemp. I do NOT recommend using bundled motherboard utilities, HWmonitor, Open Hardware monitor or Speedfan.
Let the system stabilize for about five minutes after you open the monitoring application. Note the CPU core and package temps at full idle.
Next, run Prime95 version 26.6. Choose the Small FFT option. After five minutes note the max CPU core and package temps. If at any point while running Prime95 you see an individual core or package temp go above 70 degrees Celcius immediately open the File options in Prime 95 and choose Stop all workers and then exit program.
My first guess is that the mount is not good. I have read about a few indications that mounting pressure is a little more difficult to achieve on these coolers due to the mounting design, and it seems as though you probably either didn't get the right mounting pressure OR something is interfereing with the water block/cold plate assembly fully seating on top of the CPU lid. Make sure the bottom of the cold/water block plate is not touching anything except for the CPU lid. No capacitors or anything else stopping it from going down all the way.
Also, it is fairly common for users new to AIO cooling or even aftermarket air cooling to not get the standoff/backplate assembly as tight as it should be, which will compound the problem of not getting the cold plate fully seated against the CPU lid even if it is completely tightened against the standoffs. If the backplate is slightly loose, the water block plate cannot fully tighten against the cpu. You might want to double check that you've also used the CORRECT standoffs. Usually coolers come with multiple sets for Intel or AMD, and sometimes more than one set for each of those depending on the socket used.
Some users have found that installing small plastic washers between the backplate and motherboard allows the standoff to backplate fasteners to fully tighten up a little better, which can help the tightness of the water block to CPU lid mounting pressure by making sure no fasteners are bottoming out before they are tight. This can happen sometimes because not all motherboards are the same thickness and thinner motherboards might case the stand off to backing plate fasteners to bottom out before becoming fully tightened.
In order to help you, it's often necessary to SEE what's going on, in the event one of us can pick something out that seems out of place, or other indicators that just can't be communicated via a text only post. In these cases, posting an image of the HWinfo sensors or something else can be extremely helpful. Here's how:
*How to post images in Tom's hardware forums
Run HWinfo and look at system voltages and other sensor readings.
Monitoring temperatures, core speeds, voltages, clock ratios and other reported sensor data can often help to pick out an issue right off the bat. HWinfo is a good way to get that data and in my experience tends to be more accurate than some of the other utilities available. CPU-Z, GPU-Z and Core Temp all have their uses but HWinfo tends to have it all laid out in a more convenient fashion so you can usually see what one sensor is reporting while looking at another instead of having to flip through various tabs that have specific groupings.
After installation, run the utility and when asked, choose "sensors only". The other window options have some use but in most cases everything you need will be located in the sensors window. If you're taking screenshots to post for troubleshooting, it will most likely require taking three screenshots and scrolling down the sensors window between screenshots in order to capture them all.
*Download HWinfo
For temperature monitoring only, I feel Core Temp is the most accurate and also offers a quick visual reference for core speed, load and CPU voltage:
*Download Core Temp