I've been using Western Digital hard drives since getting into computers in 1998. In fact I've never owned anything but WD hard drives (from 4.3gig to 1TB). In all my years of using them I've only had 2 go bad, though they never "completely" failed. This speaks of Western Digital's consistency in reliability.
With that said I love the Caviar Blacks and have 3 of them in my system - 500, 750, and now the new 1TB SATA 3 (64Meg cache).
While there is a noticeable speed gain over my previous 1TB Caviar Black (32Meg), the previous version was/is extremely quiet! This new SATA 3 drive is LOUD! It sounds like a percolating coffee pot at its highest boiling point, especially during boot-up or accessing files. Very annoying, especially if it's the noisiest part of your system!
I just put an i7 system in a Cooler Master HAF X case which has 4 fans - 1 Front bottom 230mm 700RPM 19dBA (Red LED), 1 Top 200mm 7000RPM 19dBA, 1 Rear 140mm 1200RPM 19dBA. My Noctua CPU cooler fan tops out at 1200RPM load at 19dBA as well. At idle my ATI 4890 video card fan runs around 27 percent, making it in-audible above the other fans.
My point.... My case is extremely quiet.... Save for WD's new Caviar Black SATA 3 HD!!! Because of this I'm seriously considering going back to my previous 1TB 32meg cache Caviar Black HD.
BTW this is a replacement drive as I thought the first drive was faulty due to the same noise. With that I called Western Digital about this issue.... and to make a long story short, they say this is normal and that drive wasn't designed with noise in mind, that if you want a "quieter" drive, get the Caviar Blue.
Make of that what you will....
All I know is that the older 32mge cache Caviar Black drives ARE quieter than their 64meg cache cousins.
Those looking for quieter WD drives might consider looking elsewhere (Blue or Green series) if noise is a factor over speed.
Edit. Went back to my previous drive because of the noise. If you want a caviar black that's quiet, go with the 1FALS (32meg) vs the 2FAEX (64meg)