As a test, find a way to have the radiator and fans in "free air". You could try something like lay the case on the side, side panel open, dismount the radiator and see if you can leave it somewhere outside the case. Then go run something like CineBench 23. This is to take the case setup out of the equation as much as possible and make sure the cooler itself is working properly.
Another thing to check is to make sure the TIM covers most of the IHS. You can dismount the CPU side for a quick check. You do not have to re-apply TIM if you do this.