MoBo: asus m5a78l
cooler: ht100 i
i want to underclock it but i dont know how to do that. and i cant find any software that i see in youtube videos. is there anything im missing that would be over heating it.
That cooler should keep temps in check more than satisfactory even with high OC. I suggest you check cooler mounting and settings as well as TIM paste between cooler and CPU. Make sure pump and fans are running at proper speeds.