The RPM rating of the Green drives says “Intelipower *”.  I could have sworn that at some point I found a detailed specification on that explained what that meant and it said that the speed was variable between 5400 and 7200 rpm, but I am hearing reports now that testing indicates they are only 5400 rpm, and I can no longer find a reference stating they vary from 5400 to 7200.  What is the deal?

Well, The link below have information about the Caviar Green RPM:

AFAICS, the information at that link is incorrect.

According to WD, IntelliPower is “a fine-tuned balance of spin speed, transfer rate, and caching algorithms designed to deliver both significant power savings and solid performance. For each drive model, WD may use a different, invariable RPM.”

This means that each model runs at a fixed speed. It is not variable. AFAIK, in the case of the Caviar Green the speed is 5400 RPM.

See this thread: