Q1: ya, it is possible. u try PM Sib. he ald done that.
Q2: use bottom as intake, Stormforce can fit to the 230mm holes of the stock fan.

@undine
stick to the stock will do
90 cfm is so noisy

Hi,
Recent owner of an ATCS840 here and I think I can answer some of your ATCS840 questions.  I use all my optional fans ncluding the 2x120mm fans at the back of the 3.5" drive cage. As the case is so huge I feel this helps with the airflow. My bottom fan is intake. I don't use the fan shroud at the back tho as it doesn't seem to affect my temps much. I also disabled the front top 230mm fan. My only exhaust is the rear 120mm and  just the one 230mm fan at the top rear. I feel having the front top fan on removes cool air before it gets to the components in the case so I had that off and covered the grill.
Another reason I did that is I prefer having a positive pressure instead of negative pressure in the case (Intake>Exhaust).
first post!

Cooling is better but not  so much due to the postive pressure - but from not connecting the front top 230mm fan  (the cool air isn't routed out prematurely but gets routed to the areas that need it) and having the optional fans installed. In fact with that fan config it's more of a neutral pressure because the only added intake is the bottom fan. I just don't like having neg pressure because it just negates the purpose of having dust filters on all intakes that already comes with the case. One of the reasons I chose this case were the included dustfilters - thus having neg pressure (dust would come in thru the gaps in the case) wouldn't make much sense which I think is a bit of a design flaw by CM. Luckily it's easily remedied by disabling the forward top fan and adding a bottom intake which is already filtered - so you get 2 added benefits: improved airflow and less dust.

I'm thinking of adding a Scythe Kama Bay at the front just above the front intake - and have cool air blow straight into the mobo area. It takes up 3 5.25" bays. One of the advantages of having 6 bays on the 840 to play with. But it's hard finding one in my area..

take out 1 top fan lo. ur temp looks normal

ur GPU temps are actually very good man...

everything else looks normal

so its actually alright