You might try connection the AIO pump to the AIO pump header (Pump at full speed all the time is fine) and then the two fans to CPU and CPU_opt. and then use Qfan control in the BIOS and set the RPM manually for CPU to run @ 1020 - 1050 RPM. I use corsair AIOs and have the fans set to follow the liquid temp not CPU so it does't do that ramp up and down thing. But I know that does not help you much. So, using Qfan control in the BIOS for your CPU I might set the fans to run @ 1050 RPM until the CPU temp hits say 70C and then bump the RPM up to @ 1250 and then to max @90c It may take some experimenting but you should be able to flatten out the constant ramp up and down. Another option would be to not use QFAN but install AIsuite 3 and use fan expert - with Fan expert you can apply a delay for the fans in seconds that can help keep them from ramping up and down in conjunction with adjusting your fan curve. Some folks like Fan expert and AIsuite and some don't. But it is there as an option and I have had success using it with my Fractal S36 on a system as the S36 does not allow me to control fan based on the liquid temp. Bear in mind also that the FAN rpms I noted are based off Corsair ML140's and have up to 2000 RPM. I do not know what RPM your fans run at so you may have to adjust to suit your cooling need and noise tolerance.

You did not mention what chassis your using or if your running the AIO as intake or exhaust or list any other factors like if you have a blower style GPU or not or if you have any other fans in the system for exhaust or intake.. So there could be a lot of variables left that are contributing to your thermals. Another thought is did that AIO come with pre-applied thermal paste or did you apply your self? If it was pre-applied you might consider removing the pump and cleaning off the preapplied paste from pump and CPU and re-paste using a compound like Noctua NT-H1, Thermal Grizzly Kyronaut or Arctic MX4. You might want to just try re-pasting anyway even if you applied your own. Also make sure you are getting a good mount of the pump block to the CPU. Have another look at your airflow too and if you are exhausting aka the rad is in the roof and you are pulling air from in the chassis and exhausting it out through the radiator - you might try front mounting as intake so that you are pulling in cooler air across the radiator, and then using the roof or rear fans for exhaust.