Hi guys, here's the quick rundown of the problem.
Bought a new harddrive for a cousin's PC. (seagate 40gb)
Installed everything on it and it was running fine for a while. Then one day he turned it on and a smell came out from the case. He opened it and found that his PSU had fried/died. After he bought a new PSU he tried booting up but couldn't. His new harddrive was dead, and the harddrive he had set as slave was also dead.
Was it more likely that the PSU caused the harddrives to die, or is it possible that the new harddrive somehow malfunctioned the PSU?
It was probably the PSU that caused the damage. A badly constructed PSU can send a surge through the system during a sudden, catastrophic failure, and that can "kill" components. Imagine a small, internal lightning strike along the rails. Your cousin is lucky that <i>all</i> he lost was the hard drives. Hopefully, no other devices will fail as time goes by, but the possibility exists.
This is yet another good reason to be willing to invest in a good, heavily-constructed PSU, instead of buying the cheapest unit that will boot the system, as so many people insist on doing. As computers continue to become more speedy, and the power demands increase, I think we'll be seeing more and more of this over the next few years. Generic 250 & 300 watt PSU's are just not enough anymore for a modern desktop, loaded with power-hungry devices. It can end up costing more in the long run, as users are beginning to discover.