I held the fans from the bottom and pressed them up to the bottom of the beams then slid the radiator bracket in place (no radiator attached). The bracket once in place kept the fans from falling down. I could then slide the fans around, hold the radiator up from the bottom, and line everything up/screw it in place.
I believe the original poster cut the beams out so he could insert the fans from the top after the bracket was in place. With some creative assembly cutting the beams out is totally unnecessary. The lips on the beams that stick down need to be cut off for this to work, but it is better than losing the entire beam.
As far as fan noise goes, I have them set to 20% and really have to listen to hear them. At 50% they are very audible, but tolerable. 75% and 100% is unbearable. I use the Asus Fan Xpert 3 app to control the speed. If temperatures increase it increases the fan speed accordingly. The only time the fans ramp up at all is when gaming they may hit 50%. When this happens I'm wearing headphones anyways, so I can't hear it.
The non-industrial Noctual fans I have used in a couple of other computers. They're pretty much the same thing, but spin at lower RPMs. Even at 100% I would say they're about the same as the industrials at 50%.
Thank for the info! By the way, how to those 3 stock 140mm case fans run air flow and noise level wise?
Similar to the Noctua Industrial. They are nearly inaudible at lower speeds and obnoxious at higher speeds. At idle/web browsing, the front two fans are at a very low speed and the rear fan is disabled. I had issues with negative pressure pulling dust into the case with two intakes and three exhausts. I don't count the power supply intake because that fan never needs to run.
By disabling the rear fan and forcing the power supply to run at 20% I have positive pressure and dust is not an issue. As soon as I start gaming or the temps rise the rear fan kicks in and the other fans ramp up appropriately.