You should seriously try increasing your fan speeds and quite possibly increase the airflow in your case (buy more, or better fans).  The FE is a blower unit which means it doesn't work better with the side panel off, it will actually work worse vs an open air cooler that throws the heat back into the case.  Blower blows the air out the back of the unit via the holes in the card.  What you should do is 2 put more intake fans on the side panel, as you have holes there already set in, though if you wanted you could play and have the bottom one set as an intake and the top one as an exhaust but would probably be best as both intake.  I would also ensure all your front intakes are also filled.  You want as much fresh air getting into that case as possible.
 
You can have up to 8 120mm fans in your case (it only comes stock with 1 intake and 1 exhaust).  I'd make sure you do, and that they have lots of CFM and air pressure to push that cool air in and suck as much hot air out as quickly as possible to help that blower card.  Lastly, pump up that fan curve.  Don't be scared.  I run 2 1080's in my full sized tower and i need to have their fans at 100% or else they will throttle down due to heat.  I do need to buy a new case, that much I know.  Currently running an ancient Define XL.
 
I would like to add I finally changed my case fans this morning, to Cougar Turbine 140mm Hyper Spin Bearing Fan 1000RPM 64.5CFM.  2 intake (1 in the front, 1 in the side panel where I never had one before) 1 exhaust.  My temps on my primary card have DROPPED 10 C.  My secondary card still has the same temp of 69C, sometimes dropping down to 65C but my primary card no longer hits 79C, it stays at 68-69C due to the increased air flow.  I used to run with an open side panel as both cards, an FTW ACX 3.0 and an MSI Gaming X are both thrower cards that throw the heated air back into the case.  Airflow is important :)