So what are some good fans for the Fractal Design R4?
In addition to the pre-existing 140mm case fans, I plan to install at least two more fans, with the intention of mounting two at the front, one on the floor, and one at the rear as an exhaust. Intakes will be linked to the built-in case controller, while the exhaust will be connected to the motherboard. Good acoustic at lower speeds is desirable.
Ideally, I'd also like them to match my colour scheme, which is black and white with blue highlights.
I know you want to match the color scheme but if you are into quietness, then take a look at the Noctua NF-S12A fans because they are one of the best fans on the market. I have four of these fans in my case I cannot hear them running even under full load. Take a look at this in-depth review.
http://www.amazon.com/Corsair-Series-Edition-Single-CO-... Corsair quiet fans, I have 2 of these 140mm in the same case. 1 on the bottom (Intake) and 1 on the top (Exhaust). Then I have the 2 stock fans in the front, and I got 2 120mm of the corsairs silents for my antec kuhler 920. And it is quiet, and very cool.