Pulsing, humming sound from Raid

[Titanion]

I have two old 30GB DHHs in a RAID0 on an NF7-S motherboard, and I just reciently noticed a low pulsing, humming sound that repeats every few seconds. It is on a 2nd computer that my daughter or friends play on, and I have only just noticed it. I unplugged each of the HDDs in turn, and the sound stopped. I thought it might have been from one of the drives, but it only makes that sound when both are plugged in. They are placed close together in a rather tight space. Is this a common thing?

 

[croc]

I have two old 30GB DHHs in a RAID0 on an NF7-S motherboard, and I just reciently noticed a low pulsing, humming sound that repeats every few seconds. It is on a 2nd computer that my daughter or friends play on, and I have only just noticed it. I unplugged each of the HDDs in turn, and the sound stopped. I thought it might have been from one of the drives, but it only makes that sound when both are plugged in. They are placed close together in a rather tight space. Is this a common thing?

Just a guess, but as they are old the bearings are probably getting noisier. One hums at a slightly different frequency than the other, and every so often they develop a harmonic. On their own it wouldn't be noticeable. If its not too annoying I'd just put up with 'til the drives die.

Maybe mount them with rubber grommets, drive cage might be amplifing the noise?