Hard drive dies then comes back to life?!?

Sooo confused. :??:

I got a used HD 4890 about 3 weeks ago from a friend and decided to put it in my Dell Inspiron Minitower, along with a new PSU of course. The Earthwatts 500 worked brilliantly with the new card, but I was getting some high temp readings (60*C/fans 50% @ idle, 85*C/fans 100% @ Crysis).

Didn’t think anything of it b/c I knew the 4890 runs hot, but yesterday morning my hard drive started clicking and the computer told me it didn’t recognize an HDD anymore. I checked all the connections and everything was fine, but when I booted it up, it would freeze and give me what sounded a LOT like the click of death. So I cursed Dell for using a cheap HDD and read all afternoon about hard disks dying because of temp problems (my case is NOT well ventilated) and just resigned myself to buying a new one …at these horrible current prices.

I also read something about high wattage video cards stealing power from hard drives, so I swapped out the HD 4890 for my old HD 5670 (also switched to a different 4-pin molex), thinking I had maybe a 1 in 1000 chance that was the problem – and my hard drive sputtered back to life! It clicked for a bit, said it couldn’t load the OS, and then asked me if I’d like to repair my Windows 7 install with a system restore. Since I restarted, there has been no more clicking! Took longer than normal to boot, but now it’s working just as it always has. I quickly made a fresh backup on my USB drive, but there are no signs anything is/was wrong.

Can anyone figure out what in heck happened to me? Apparently the heat didn’t kill my HDD (though I’m sure I shortened its lifespan), so I guess it was a power problem? But why would it work fine for 3 weeks, then?