Hi,
I havent built a machine in ages and it seems im now out of touch 

  My new Mobo has an 8pin power( ATX 12v 2x4)  socket and the 24pin, My PSU has a 24pin plug and a single 4pin 12v.  Do i need to add another 12v to fill the 8pin?
Incidentally its for a 3.2 Quad Phenom II
Thanks