You need to heat the chips until the solder remelts (around 800 degrees i set my gun to 805). anything less will just get things hot and not melt anything.. and the "chips" your heating aren't exactly the chips those are heat plates that transfer heat to heat sinks. the chips are underneath.
So you have to get it really hot quick so everything melts back. And IMO 5 to 10 minutes is way too much time, I heat mine about 20 seconds then move to next chip, 20 seconds there and back to first chip for like 20 more seconds about 1/2 inch above chip always moving in a circular motion SLOWLY.
PS Make sure you use a no clean liquid flux before you heat it so the solder don't crystallize and crack quicker after the repair.