Frequent Hard disk Failures in Vostro 3681

Hi 

So far I've purchased more than 20 Dell Vostro 3681. and this model desktop frequently faces the BSOD with an Error_MSG: No Bootable Device Found.

Every time I had this issue, Dell Support says its not a Hardware issue but a Software issue. But really it seems to be the hard disk issue only. Every time it happens I lose the user's data....

Kindly Investigate and give me a solution to this problem.