what do you have the fan plugged into? is it the cpu fan header on the mobo? If it is, make sure, in your bios, that the fan is set to spin up at a modest temp, something like 50degrees Celsius, all the way to 100%. What are you running for a CPU? What are you using for a TIM? I've never used a stock cooler on either an Intel or AMD chip, but if it's an intel, I know you have to get all four corners to click firmly, or you won't get a good contact on the CPU. Some of this is amateur level, I know, it's just that I can't count how many times, on this forum, that the issue is solved when the OP double checks the connections on the cooler.