Open terminal and copy and paste this -
yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null &
It’s known as a yes command. Paste it 4 times, that will max out all your cores, when you’re done testing, type in -
killall yes
That will terminate the yes command.
Let us know how you get on. You’ll know for sure how good your cooling is this way.
Would you have to do it 6 times for 6 cores?