I don't know a whole lot about your problem, but I do know about air circulation. First off, let me start by saying that you should probably tell us your processor idle temps, and full load temps.
Air Circulation. You said you have
2 in back sucking out air.. 4 in front sucking out air
They should not all be sucking out air. Also, if you meant 4 in front pulling air in, you don't want 4 fans pulling air in and two pushing it out. You want close to a 1:1 ratio. See if you can do one of these solutions.
1) Two front fans and a side fan set to intake. Two back fans and a top fan set to exhaust.
2) Three front fans set to intake. Two back fans and a top fan set to exhaust.
3) Two front fans and a bottom fan set to intake. Two back fans and a top fan set to exhaust.
(Option 1 is probably your best option) The top fan as exhaust is good because warm air rises, and it'll blow it out. If you do not have a hole for a side fan or top fan, I recommend getting a better side panel for a 120mm fan on the side. If you are going to work with the case you have, then try setting three front fans to intake, and three back fans to exhaust. If you cannot do that, then you need to probably disable an intake fan. You want the computer to blow front front bottom to back top. If you have too many fans set up as intake, then you'll greatly increase the pressure inside the case, which makes things overheat. If you can do one of the first three setups that I have listed, I'd recommend getting a different case using these guidelines to determine if it is good.
1) Has enough fans... probably a minimum of four case fans.
2) Has room for a 120mm fan or two. 120mm fans circulate air much better.
3) Look for a fan spot on the top of the case to get rid of the warm air that rises.
4) Make sure there are spots for fans on the front AND the back of the case.
5) Look for a side panel fan that can be set to intake. This feeds fresh cool air from the outside right to the processor fan and other fans that it may be blowing on.
That pretty much sums it up. Remember to keep your ratio as close to 1:1 as possible to get good airflow. If you have an odd number of fans, you'll probably want more set to exhaust to get rid of warm air. When it pulls air out, the cool air from outside will get pulled in somehow (physics). However, if you have more blowing in, then hot air pockets tend to build up, and cool air is expelled instead at times. This could cause some heat problems.
I hope this helps.