How to reflow the right way
reflowing with a hot air gun is risky because the heat is not uniform around the chip causing hot spots and warping of the board and chips
to reflow properly you will need:
.A hot air reflow station
.a stand to hold your hot air gun
.thermometer with 2 thermocouples
first you need to prep the board buy removing any left over heat paste. Then put the board on the preheater
making sure when the gun is lowered the nozzle will be over the gpu/cpu. preheat the board to 170c to 180c if the motherboard is warped preheating for half an hour an reduce the warping.
Then you need to turn your hot air reflow station on i start at 160c increasing the temp by 3c every second until the top of the gpu /cpu reaches 235c hold it for 15 seconds.
then turn the preheater off and the gun allow to cool for 10 minutes
i have had good results using this method