possibility of negative pressure.

[Barrdock]

if i put 2 intake fans and 2 exsaust fans(top and back)is possible to have negative pressure?And can you tell me if coolermaster sickleflow are good fans?

 

[KR2]

if i put 2 intake fans and 2 exsaust fans(top and back)is possible to have negative pressure?And can you tell me if coolermaster sickleflow are good fans?

I would have 2 fans at the front and 2 fans at the back because that is the most effective in my opinion. I would get Noctua fans since they are very nice quality and will last you a long time.