I have a previously functional hard drive that is no longer recognized by the BIOS. Other drives are working fine. Just not this one. It has no scary clicking or grinding noises. It sounds lovely, in fact. Normal health read and spinning sounds. It even has the gyroscope feel if I pick it up. Stuff I have tried unsuccessfully: *Restart the computer *Restart the computer again just in case *Swap out cabling *Use an external power source *Use a SATA-to-USB adapter *Use a different motherboard with a different BIOS and a different power supply *Use a different motherboard with the USB adapter *Swap out the controller board for a new one--same model and revision, but stole the flash memory chip off the old board so it had its calibration information right. I'm thinking that the platters and read head and all are good. I seem to have ruled out the controller board as the culprit. Anybody have any ideas what might be the issue?