...I still feel that I can't fully enclose the drive with out some sort of active cooling (50C max with 8.5 watts at idle). I looked at the sound specs and they should be quiter than they seem -- 3.9 to 5.0 bels. (can anyone tell me how to conver bels to dbA?) Perhaps my "pulsing" noise is from something else.
BTW- the drives were 30 bucks from TigerDirect, if anyone is interested.
I checked the power consumption of my maxtors. They do 7.4 watts at idle/12.5 watts seek. Pretty close to yours. If you build a tight fitting rubber box and use a healthy amount of thermal paste, the rubber will acutally conduct the heat away from the hdd's. The only issue is that the rubber needs a fan to carry the heat away (but not at full voltage mind you). Look at my sig, those hdds temps are when my drives are seeking heavily and with a Panaflo @ 6V blowing on them.
EDIT: there's no formula that I know of to convert bels to dB/A, but my QAD method to get a general idea is to multiply bels by 10 to get dB.