Set the motherboard on a support so that the CPU and GPU are completely supported and level.

The support should be something that can resist temperatures upwards of 300 degrees Celsius. Suggestions: scrap lumber, old books, cardboard box.

In the next few steps, you will be reflowing the solder under the chips marked in red.

Once you begin reflowing the chips, do not touch or move the motherboard until it is completely cool. Doing so can render the motherboard irreparably damaged.