I have an old (2006 manufacture date) Western Digital Caviar SE 250 GB with a SATA interface that I pulled out of a system that wouldn't boot. Further testing revealed that plugging in that drive into another known good system, with another drive set as the main drive prevented the system from booting and be stuck in the boot sequence and the drive would 'click' repeatedly.
Now, if I was to plug in the drive after post POST, either in BIOS or in an OS, it detects. In Gsmartcontrol, the drive shows a lot of prefailure or old age (well, all flags are one or the other) related flags. It passes the quick self check, but the full one fails. Drive appears visible to the OS, as are the contents, but i didn't bother to check if the contents were retrivable (since it was a bare OS install).
So, why would a drive having what's obviously mechanical failure keep a system from posting? I'd be willing to run any (free) tests I could run on a linux system if need be, but this seems lower level. Electrical/system failure is contraindicated by the drive apparently working fine after the system boots, but there's no other reason for it to stop the system from booting.




