Welcome to the forums, newcomer!
We're going to need more info. Please list the specs to your build like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
include the age of the PSU apart from it's make and model. BIOS version for your motherboard at this moment of time.
temps under barely any load have gone from 30-35 to 45 but under heavy load its way cooler though gone down about 30 degrees
Did you manipulate the fan curve for your CPU cooler while you were on the Coolermaster cooler?