Mac Pro optical drive problems

Question

I have a 2009 Mac Pro and have been having problems with optical drives I've installed in the lower bay. I initially installed a Toshiba drive that had Lightscribe technology, as I needed this for my wife's business and my Lacie external Lightscribe drive finally died. This drive worked great except for a loud "click, click" noise that it made every few minutes when not in use. I had originally attributed this noise to a hard drive starting or stopping but after repeated attempts to isolate the drive were unsuccessful, I resorted to using my old mechanic's stethescope and the noise seemed to be coming from the lower optical drive. I confirmed this by opening its tray and leaving it open which got rid of the noise. It was a very annoying noise, easily heard in my bedroom across the hall when the machine was asleep (and I wasn't). I decided to change it out for a Blu-Ray drive as the prices had come down out of the stratosphere. I bought a Pioneer drive from OWC and after having it disappear and reapper on me, behavior verified as a problem by checking these boards, I exchanged it for an LG unit. This one works fine and seems to stay recognized by the Apps that use it but a "click" is back. This occurs with about the same frequency as the Toshiba but is a single click and is much quieter. There is no periodic noise from the factory Superdrive. Someone suggested somewhere that this could be caused by Spotlight trying to access the drive. This doesn't seem logical as the noise only happens when there is no disk mounted. Would there be any software that would periodically "ping" the optical drive, even when the system was asleep? I can live with the noise from this one but am still curious if others have had this problem, and may have come up with a solution. Thanks, Ted
The drive installed now is an LG model number: WH12LS39KMP, the previous noisy drive was a Toshiba SH-S223

Answer 1

Repeated starting and stopping hard drives is not a good idea, and should be limited to laptops running on battery power.  With most, the heads rub on the discs while starting or stopping.  Drives specs usually allow only 25,000 to 50,000 starts.  Temperature changes between running and sleeping puts stress on electronics, and can cause earlier failures.  Also the starting current stresses the motur circuitry.
Apple optical drives have special firmware.  If you look in the "ATA" section of "System Profiler" (Utilities folder) you should see that the Apple supplied drive supports "Low Power Polling".  This may be why Apple optical drives don't have problems with drive sleep mode.