SATA HDD not recognized? Optiplex 790 (solved)

So Im trying to upgrade my old Optiplex 790 with a higher capacity HDD.. I currently have a WD2500YS (250GB) and Im trying to replace it with a Barracuda XT (2TB) drive.. They're both SATA 3.0 so I figure just plugging it into the existing cabling would at least get it to be recognized? Updated BIOS to v22, tried all configs of different cables, boot types, etc. Unplugged everything else (DVD/RW) so the only thing getting power was the HDD. Still nothing. Just stops boot with NO HDD FOUND.. I got into the bios at open up the devices and it's just 0+0+0 I can put the old WD back in and alls fine? The Seagate will spin up as soon as the power button is pushed, but idles down and then I get the error and have to enter BIOS (F12) Once in the BIOS it doesn't see it at all. Is there anything to assume, other then the HDD is DOA?? I got it used off ebay, but from a reputable dealer.. I want to think it's the Optiplex, but keep going back to the fact that I can swap it out with the western digital, which works fine, the BIOS see's fine, etc.? Thanks for a direction.. Mick