Question : Problem: Why is there a magnet around case wires that connect to motherboard?

You know the wires that come from a computer case (POWER, SPEAKER, HD LED, etc.) that connect to those pins on the motherboard?  I have been working on some computers that have those wires wrapped around or passing through a magnet.  Can someone tell me what the purpose of that magnet is?

Answer : Problem: Why is there a magnet around case wires that connect to motherboard?

They aren't strictly  magnets, they are made of ferrite.
Pretty much everything you could want to know about ferrite beads here:
http://en.wikipedia.org/wiki/Ferrite_bead