So I replaced the stock NORCO 80mm Fan Blade with a new 120mm fan blades I bought on Amazon dot com. It has reduced the noise significantly... almost to a whisper quiet. The cooling temps seem to be unaffected. A huge win!!!
The stock fan blade uses 4 80mm fans that run very high. They are powered directly off the PSU with IDE power by default and have no fan speed control. They run full bore 100% and make tons of noise. They also move tons of air.
I opted to go with silent X fans because they are cheap and quiet, and I could run them off the motherboard headers:
Here is the comparison:
This the fans I bought:
They run lower voltage than the stock OEM ones making them quieter, and also have header pins for running of your motherboard versus just plugging into the PSU IDE power. Of coarse using the fan control to slow them down also greatly reduces the noise. XIGMATEK eXTREME SILENT Series have FCB (Fluid Circulative Bearings) which seems to quiet them down (MFG claims) and they are highly affordable. Much cheaper than the NEXUS.
It's funny because the stock OEM ones are nearly identical to the ones I bought. I assume they are made at the same factory, which just different bearings and motor/designs. The outer plastic shell and case is identical to each other, but specs are different.