I’m always struggling to desolder high heat circuit boards like pc motherboards because they used high heat solder. Sometimes I can get it hot enough that I can mix in some lower temp solder but it’s always a pain. I’ve also used my rework hot air at 500* plus the soldering iron at 500* and gotten it, but that’s a pain as I only have two hands. Right now I’m replacing the Nec/Tonkin caps on a ps3. Fortunately removal is simple with a chisel, but getting the pads ready for soldering is a huge pita.
For multi layer PCBs like motherboards, you want a PCB preheater in addition to a good soldering iron. The ground and power planes will take a lot of heat. If they are already warm, they will need less heat from the soldering iron.