I have a gigabyte mobo. The purple are for RAID only. If you do not run RAID then orange connect them. Go into the bios and enable all of your SATA ports. You should be good to go once you get the bios configured properly.
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EVGA 680i, Dual EVGA 8800GT'S (650/950), 4 gigs OCZ DDR2 1066, Intel Q9450 at 3.8 Ghz, Koolance Water Cooled, Dual Plextor16x DL DVD+/-RW. Dual WD 250gb 16mb Cache Sata 3.0. 3DMark06 score = 19,168.