what fans would you recommend using with the aquacomputer modular rad
In regards of your question about what radiator fans to use? Well this vary but generally look at fans who have high pressure. Personally ive done my research and my choice will be (note here these are 140mm fans)
Noiseblocker NB-BlackSilentPRO PK2 (there are 120mm version of this fan)
https://www.amazon.com/Noiseblocker-NB-BlackSilentPro-140mm-Ultra-Quiet/dp/B002UJKRCU
Review on various 140mm radiator fans which the above fan is placed at nr 1.
http://forums.bit-tech.net/showthread.php?t=199499
There are however other good fans to chose from Noctua, EK, Corsair i went with Noiseblocker because it has been developed with water coolers from Germany wanted to have a good radiator fan noiseblocker asked for feedback with the water cooling community in Germany namely
www.Hardwareluxx.com. The result is the PK-2 fan. You also get allot of accessoires with the fan.
If you really want more feedback on which brand of fan to use on rads i suggest making a new thread and see what people suggest you make sure what type of fan you want ie silence, performance etc.
I also suggest using a proper fan controller which you can connect 2 fans per channel like the "Lamptron FC-5 Fan Controller 4x 30W Channels Black V2" so you can adjust speed to 500rpm - 800rpm.
If you plan on water cooling both your cpu and gpu that rad you posted on your first link (240 rad) won't cut it i would suggest go with a quad radiator atleast.A tripple would do but you want high rpm fans and this means more noise. The more rad space you have the lower rpm fans is needed and also more heat is dissipated. Here is the version you might be interested in its a quad rad: (make sure its a SINGLE circuit)
http://shop.aquacomputer.de/product_info.php?products_id=2886
Now it depends on your budget other good radiator brands are XSPC radiators ( i used a XSPC RX480 for cpu and gpu with great results) and HardwareLabs radiators HWL from my research also makes one of the cleanest rads and are performing really well ive posted the name in my previous post.
These are cheaper solutions but cools great!:
http://www.performance-pcs.com/xspc-rx480-quad-fan-radiator-v3-black.html
The HardwareLabs Black Ice SR2 MP 480
Had also doubts about which pump to use and the feedback i got is go with a D5 pump with top+res since that pump is reliable, powerful, and silent for example this :
http://www.performance-pcs.com/alphacool-vpp655-single-edition.html
And then use a good top + res for example:
https://www.ekwb.com/shop/ek-xres-140-revo-d5-pwm-incl-pump
Some people used the D5 with like 4 water blocks and 2 rads without problems and still have decent flow.
From what i gather its best to buy the top and reservoir separate.
There are some anecdotes from people using EK D5 pumps which where noisy while the Alphacool D5 where very silent and i can confirm the Alphacool are silent ive tested it and pretty silent at setting 3.
Another pump if your planning to cool more then your cpu and gpu and want to add more blocks is a high pressure pump like the DDC or more specific a Swiftech MCP50X very good for high restriction setups but do not know the reliability for prolonged time generally a D5 pump is best can go on for years and years. That to me is important plus the D5 gets its cooling from the coolant while DDC pumps needs external cooling.
Lastly went with the AMS rads because i was done with flux crap ending up in my blocks even though the AMS might cool decent as some reviews tell us bit confusing since other reviews tell us it performs greatly in anyway i just went with it with a monster AMS rad 840 (6 x 140) which should allow my setup to run at very low rpm fans 500rpm range. The D5 should have no issue with this albeit restrictive rad plus 2 water blocks at all since some people used the D5 with so many blocks and rads without issue see link:
http://www.overclock.net/t/1606165/whats-the-most-you-have-cooled-on-a-single-d5-pump
Whatever you do flush your rads before use any rad that is.
Hope this helps