m_zeid wrote some people put the board in the oven to do reballing hahaha
The oven method used when you know there's a broken solder joint but you don't know where exactly, it's a hard way and a bad idea since you need to remove all plastic parts from the board.
Using a heat gun is a lot easier, just cover the whole board with multiple layers of alominum foil except the GPU to prevent any damage while heating it up.
I've done this many times on video cards/motherboards/xboxes...
One time I've fixed a 6600GT GPU using a cloth iron ! LoL ;)