Sorry to hear you unit has problems. you need to check the serial number sticker on the outside of the box since the serial is based on the manufacturing date .
In my case, I recently bought a H100 from amazon, it has the serial # 12269403 and it made no noise, actually it was very quiet but then again since I have not finished building my computer I could not do a full install so I connected the h100 (pump and fans) to an extra power supply I had laying around, still got my fingers crossed that when I do install it I will not have any issues.
Regarding interpreting the serial number in order to understand when your unit was manufactured :
The first 4 digits of the serial number are the manufacturing date, in my case with a serial 12269403...12-was built on 2012, 26- the 26th week of this year, meaning that my unit was built around the last week of June 2012.
What this old means is that the newer your unit, the more chances you will have that it will not have any problems.
Perhaps someone here will post the date when Corsair started shipping the revised versions so you could keep that in mind when you receive your RMA.