50 PSI (3.5 BAR) is the pressure.

Also what is lower RPM do you mean like 50 cfm or 25 cfm or 75 cfm. As for the Radiator I will go for Feser X-Changer both a triple and a quad radiator.

I want to know what the best fans are I have been look at 2 different models.
http://www.quietpc.com/gb-en-gbp/pro...kazejyuni-1200
http://www.quietpc.com/gb-en-gbp/pro...kazejyuni-1900
Either one of those two would be great.