New system build...p67 extreme 6...core i5...boots but will not detect hard drive or cd drive...wd750 caviar black...replaced drive with known working drive (caviar black 640) nothing...jumpered both drives every which way...nothing...swapped PSU...from known unit...nothing...cables are new...panel header is right...I believe....antec 300 cases in both boxes...1 case has 3 pin power led header...new case has two...have tried all combinations...nothing...

Help is appreciated