Power Requirements / New Power Supplies / Heat Sinks / Cases, Contuinued
Intel even defined the place where the processor is supposed to be placed on the motherboard (right at the edge), but many motherboard makers preferred to go their own ways. Asus for example considered it to be technically better to have the processor more in the middle of the board. In return Asus ships those board with a metal back plate, which makes the motherboard boxes surprisingly heavy. The heat sink is mounted though the board to this back plate, thus ensuring stability. Asus ensures that its P4T motherboard can still be mounted into any kind of computer case, but I've got my doubts if all of the el-cheapo cases will indeed be able to host it.
Gigabyte's beautifully blue GA-8TX is placing the Socket423 where Intel wants it, but it ships the board with heat sink mounts that are fixed to the motherboard with some plastic nipples.
Future Pentium 4 processors that run at 1.6 GHz and more require their heat sinks to be grounded (connected to Vss) to avoid EMI. To ensure this board makers have to place ground pads around the mounting holes of the heat sink, as you can see in this picture: