Thanks for looking into that
🙂I'm using a Thermaltake Armour+ which does have an optional 140mm exhaust (not installed though) in the roof along with the 2 traditional intakes you mentioned. I guess... If you did install (or I for that matter) a 140mm exhaust in the roof it would completely change the airflow. Adding suction from the top would enhance the flow of the intakes and cause the heat from the RAM and Z77 to get pulled up instead of across and into the GPU's.
The I/O problem still persists though, I would recommend having that as an exhaust, NOT and intake, this would add "suction", decreasing the airflow slightly to the Z77 and RAM, true. But the benefit is that if you are running monster GPU's, they will not affect your CPU.
Edit:
Just to clarify I don't mean just stock fans, using a fan like this would benefit the Sabertooth:
http://www.novatech.co.uk/products/components/cooling/rr-gmm4-16pk-r1.htmlHowever a fan like this would render the vents under the armour completely useless and only used by the tiny I/O fan:
http://www.novatech.co.uk/products/components/cooling/cpucoolers/dcaco-fp701-csa01.html