There is no way that case will keep will keep 4x cards cool unless they are runnning in a freezer. Hell my HAF932 has issues with dual gtx 470's if it's hot out.
1st the case is open. 2nd i cuted the plate that holds the motherboard, leaving enougth steel to keep integrity . 3th the mining/render rigs r on the basement. where i have A/C and i leave on a place where the average temp is 6 °C. the cards run now at 56°C~66°C and now the temperature of my building is better the other ppl thx for it. an average of 16°C. without turning on the Calefaction.
note i have 6 running now. 6x4 gpus stucks at customs. i m8 need to pay a fee to get them out. exceded the limit per person on the import. lols
EDIT:
for those having problems with the 4th CARD and this MOBO try upgrading the bios
you can find them here http://www.msi.com/product/mb/890FXA-GD70.html#?div=BIOS try with 1.6 or higher.