Overclocking
Once Overclock Production is unlocked in the MAM you can extract more ore from your node. In this video you can see how I double the production of my normal iron node by over clocking the miner to 200%, hence allowing me to build more smelters and constructors.
Underclocking
Underclocking is utilized in this video to match Mk. 2 conveyor belt speed, hence allowing optimal use of the extracted ore.