I am not sure what exact cooler model you have but I will assume it is something like this.
The AQUAFUSION series 120mm radiator version comes with one 120mm SquA RGB fan is an AIO CPU liquid cooler, featuring superior cooling performance (300W TDP).
www.enermax.com
Enermax says this 120mm cooler can handle a 300W TDP CPU. I think that rating is overly generous for a 120mm AIO but even still, your CPU is overheating at only 75W. How old is your cooler? It could be plugged up inside and not working anywhere near its rated capacity or perhaps the pump is half dead.
What thermal paste did you use and how did you apply it? When did you install this AIO cooler?
Your undervolt appears to be working correctly. You either have to improve cooling or slow your CPU down to prevent it from overheating and thermal throttling. Any half decent air cooler is typically a better choice at the 75W power level that your CPU is running at. Much better long term reliability compared to most AIO coolers.
I understand dropping my Turbo Ratio Limits will help but from what I was told that will dramatically decrease my performance.
Don't believe everything that people tell you. Do some proper testing. A lot of people use ThrottleStop to slow their CPUs down so they produce less heat. Many games are more GPU dependent than CPU dependent so performance barely decreases. Check the Speed Shift box in the TPL window and lower the Speed Shift Max value to control the maximum CPU speed.
As an alternative, lowering the Turbo Ratio Limits in the FIVR window should also work. I prefer this method. You can lower the turbo ratios to as little as 32. Somewhere around 36 or 38 might be a good compromise. There will be less heat without too big of a drop in performance.
