assassin5675 :
So I don't have to get rid of the paste from the heatsink? Can I get any psu that fits with my pc but I don't know if I need mini itx or mini atx
old paste has to go and new paste installed.
new paste from a tube or pre-applied to a new heatsink but it HAS to be NEW paste.
the paste when installed is fluid and will flow readily finding all the nooks and crannies. when heat is applied it will cure, thicken, harden, solidify, and once removed all the nooks will not match with the crannies and you will have air pockets - again cooking the CPU.
if the paste is thick scrape off what you can and use rubbing alcohol and a lint free cloth to remove any remaining traces of old paste. the CPU will likewise need to be cleaned if not already.
install the CPU into the socket
apply paste to the CPU center, small pea size drop
apply heatsink to the CPU, gently press down - forcing the thermal paste to flow from the center of the CPU- and secure the cooler to the motherboard. the retention mechanism will further apply pressure flowing the paste.
do not remove the cooler once it is mated to the CPU, doing so could create air pockets in the paste inhibiting its ability.