Please correct me if I am wrong here but this is just what I thought after looking at it to buy.
1. I/O intake fan. Traditionally rear fans are exhausts. An intake on the I/O will pull in warm air rising from the GPU exhausts and send it to the CPU if it ever makes it, which brings me to #2.
2. Is the I/O fan really powerful enough to pull in air and push it against the flow of the air from the CPU fan? The CPU fan air will go down, hit the CPU and want to go left and right evenly. The air going left will push against the I/O fan and most likely be powerful enough to push through the airflow. If not, at least create a static "wall" of ever heating air next to the CPU.
3. The CPU air that goes right will hit a solid wall (the furthest left stick of RAM), working its way round will flow past the other 3, cooling only the edges if you are lucky.
4. The southbridge (let me be retro...), the air flowing down to the Z77 will already be heated and once past will flow out the right hand side of the motherboard and INTO the hard drives (or at least where they are commonly stored). Should you have an auxiliary intake on the inner side of the drive bays the situation is even worse. The hot air is then mixed with the cool intake, disrupting the flow and creating warm air. Which of all places, is then pumped into your GPU. (now re-read point 1)
Those are just a quick few off the top of my head. Please disprove me. I do really like this board and want to get it, but these design flaws are holding me back.
If anyone who has this board can disprove me by testing this out, PLEASE DO!
The testing that I did with the Sabertooth clearly showed benefit with the active fans in their current layout. True I did not use a stock Intel fan. And that seems to be the key to what you are suggesting here. Might have to pull out a stock cooler and see how that works.
Airflow patterns are influenced by the case that is used too. And that is the big variable. Some cases have top exhaust as well as the more traditional 120 exhaust fans. Most cases now days have a flow pattern that brings fresh air (cooler) into the case from one or two points, form the front intake and also a side intake in some cases - this air is then transported across the motherboard and vented out by the different exhaust fans. Again two is the norm with gaming cases these days. The flow patterns that you have identified would be complimented by that trend I suspect and not work in opposition to them.
To help us help you - please provide as much information about your system and the problem as possible.
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.