960GC-GS FX Serial ATA port problem

I own a 960GC-GS FX board with Bios ver P1.40. I initially had a Seagate Barracuda 1TB which started slowing down and often was taking extremely long to access any file. It was also refusing to show up in the Bios. My obvious reaction was that it was dying down as it was 6 months beyond 2yrs warranty cover. I replaced it with Seagate Firecuda with a 5 yr warranty. Initially for 15 days the Firecuda 1TB was working ok but all of a sudden it stopped working(apparently). Seagate promptly replaced my Firecuda 1TB but the replaced-refurbished unit refused to work at all. I could install an OS on it from a usb flash-drive or DVD ( SATA -DVD drive) but everything freezes after the first reboot(when it boots from HDD). I have tested both the HDD (my old Seagate Barracuda 1TB and replaced Seagate Firecuda 1TB) on my friends PC and it works fine. Do I have a problem in my SATA port . If so then how come I can boot my PC from a Ubuntu Live-CD and also type out this very query in the forum. After all I have a SATA-DVD drive. I have tested switching SATA ports but my HDDs refuse to function properly. Where the problem lies ???? How can it be solve??? I have also reset the bios in hope that would solve the issue but all in vain. Any help would be appreciated.