How to know if a CPU is going bad?

there are a lot of diffrent ways people use to put on thermal paste.

first start with attatching the backplate of the CPU cooler to the motherboard, follow the instructions that came with the cooler, put on the backplate with the motherboard out of the case if you do not have a case with a cut out at the back to attatch the retention plate for the CPU cooler.

once that is on, with the CPU in the slot and secured put a small amount of thermal paste in the center of the CPU, if the thermap paste is already applied to the cooler you do not have to do this. just a little more than the size of a pepper corn is usually enough.

some people use a plastic card or a clean bag over one finger to spread it out to cover the whole CPU evenly, some people just leave it in the middle and let the cooler spread it out. you can choose which ever method you wish.

once the thermal paste is on put on the heatsink, it should be quite tight on the CPU. make sure that it's evenly tightened when you put on the retention bracket.