HDD vibration among the same brand, same drive

Hi everyone,

I now have 3 identical Hitachi Travelstar 500GB 5400 drives (same model, made in Thailand, Apr11/Aug11/Feb12 manufacture dates) . Two of the drives are absolutely dead quiet, but one has noticeably more vibration. I had wondered for a while if I was tempting fate, but what reignited the concern and prompted this post is the latest and oldest purchases are the dead quiet ones, while the middle purchase has the steady vibration. I also think there's a bit more noise while its doing its thing compared to the other two. All of them are being used in external (aluminum) enclosures, so it's quite easy to feel the difference.

So, am I indeed tempting fate or should I consider this normal tolerance? Any thoughts or advice appreciated. I do like these B9A300 drives, so one dud isn't going to throw me off the brand.

By the way, all these drives were purchased in China, so I wouldn't bother with the warranty...just chuck it and start over. Yes, they're genuine and I could deal with it -not a blanket criticism about customer service or warranties here in the PRC- but it's just not worth the time/effort.

 

Bought a 4th drive with the same manufacture date as the third one. Dead quiet; can barely feel it running. Out goes the noisy second one. Thanks for listening