I have to admit the noise level is as loud as people have been saying. I have been deciding how I wanted to approach quieting the system down. I figured I would start researching the fans a bit since I am not too familiar with the whole system cooling scene. Thanks for the close up pics of all the fans btw, that really helped! I started with the specs for the stock case fans. The 5 case fans are Sanyo 80mm fans model 9G0812P1G09, they are 90.3 cfm and 51 dB.
The stock 900w power supplies use a Sanyo 40mm fan model 9CRA0412J505. I couldn't find specs for that specific model but I did find a couple of models (ie 9CRA0412J501) that had similar details (12v 1.4a). The similar models are 37.8 cfm and 62 dB. I feel pretty confident that matches the noise coming from the system and is pretty significant, especially with two of them running.
To have something to compare that too, I found a few decibel rating sites that mentioned normal conversation is around 60 dB, refrigerator hums around 40 dB, whispers are around 20 dB, a washing machine around 75 dB, and a lawn mower around 90 dB. Decibels are logarithmic so a few decibels difference can be relevant.
The Arctic Cooling F8 PWM 80mm fan's used by the original poster are 28 CFM and are 21 dB. That is a huge improvement. It is 1/3rd the CFM but it still gets the job done for him so I think I am going to go a similar route. I don't expect the system to run hot and I keep it in a room that is usually close to 60 degrees. I figure the fans are so easy to pop in and out that if the system temps to high I could always pop them back in. I figure it is worth it for a 30 dB drop in volume. I looked at the Noctua NF-R8 80mm Fan as well and they are 31 CFM and 17 dB. I am having a hard time quantifying what the difference between 21 dB and 17dB would be. It can be hard sometimes to find the line between what is needed and what is overkill. I will probably go with the less expensive model.
I figured since I had all the numbers handy I might as well post them in case they are useful to anyone. I didn't research the HSF yet so I don't know where that stands. I think I am going to order my new fans and then start looking into what sized power supply I actually need and go from there. Thanks again for the awesome thread, tons of interesting info stashed away in here. I can't wait to play with the IPMI stuff