I have a Carillon AC1 in my rack right next to my studio chair. I've found you don't even need to have an elaborate setup to reduce noise if you take a few things into consideration.
Firstly, using a graphics card with a heat sink instead of a fan is a good idea.
Second, use a super quiet power supply like a Zalman or a Kingwin fanless.
Third, swap out your cpu fan with something like a Zalman 7000C or a Nexus something or other.
You can also swap out your stock case fans with quieter ones but I have found that it's often not necessary to have any at all if your CPU fan is a good one. Some cases need them, some cases don't.
The only noise that you'll experience after all that is HDD noise so it's a good idea to only have the minimum amount in your main recording machine, i.e. system drive, recording drive, and sample drive. I would put your backup drives either in external enclosures or in another computer networked either wirelessly or in another room via ethernet.
One more thing is that often the case has a lot to do with how much noise you get. One of the quietest cases I have ever heard is an Antec P182. With the above components it was WHISPER quiet. We had one with a rezorator CPU water cooler and it was virtually silent.
Cheers