Hard drives throbbing
 

Firstly, get your mind out of the gutter. :Graucho

My desktop has 3 x 750GB hard drives and I can feel a rhythmic throbbing, presumably due to the beat frequency of vibration between the different drives. It's also audible if you listen really closely.

I'm concerned this is going to shorten the life of the drives.

The drives are in a coolermaster "4 in 3" cage which has the drives in a box with rubber grommets between that and the part that connects to the PC case. The drives are not individually "grommetted" which is probably the reason this throbbing is happening in the first place.

Anything I can do? A previous setup with 4 x 300GB drives did not have this issue.

That shouldn't shorten the life of the hard drives. The only way to get rid of that 'throbbing' is to suspend the drives individually with clothing elastic or stretch magic, or you could setup a NAS box and put it another room out of earshot and have just the OS drive in the computer.

So it's a known issue? I've never run into it. I have 4 other PCs next to me and they all have at least 2 drives, one has 4... haven't noticed it on them.

BTW... I'm paranoid because I've experienced an unusually large number of drive failures in the past couple of years. The most recent one is a 750GB WD which although was in another machine, is the same model that throbs in the desktop. It failed with a servo error 8 days after it was installed.

It's a rare but known issue that can happen with a particular combination of drives running at slightly different rpm's. A difference as low as 10rpm is enough to cause the throbbing noise. But like I said it shouldn't do any harm to the drives. It can however harm your sanity. :)

If the noise is bothering you, you can suspend the drives as I said above, it's almost guaranteed to end the noise and also vastly reduce the seek noises. You can also unplug one drive at a time to find the culprit, then swap it with one of the the drives in the other cases. It could make the other case start throbbing too though.