If everything else mentioned above has ben checked off.....
Go to clark rubber and get some 10mm deep/15mm wide length of soft rubber. They have it in rolls, cut this up and stick it around the edges of the shroud, this will space the shroud back the necessary 10-15mm from the edge of the core that is needed to allow the fans to draw from thee outer edges of the core instead of just where the fans sit. By the sounds of it the shroud is blocking the air passing through the core properly and is only allowing it to pass theought where you have the fans which sound very low in CFM. The whole exercise will cost you 20 bucks for the rubber and contact adhasive needed to stick it to the shroud, even if you then upgrade the fans down the track the shroud will be fine to take the higher CFM and act in the way it was supposed to.
cheers
Nath
Bookmarks