Whilst it is a good idea to supply the 2x4 with the full connector you can getaway with just plugging in a 1x4.. This needs to go into pins 3,4,7 & 8 om the MoBo (check your manual for pin assignment; page 24 in my manual.) The board will run OK but I would be careful of Overclocking or of running to many add-ons. Don't try to run the board without this connector!
Hope this helps