Now why would anyone want to keep door open? That would let noise out.Do you have it on all the time with the front open? Otherwise surely that's going to be restricting the airflow a fair amount?
I never keep door open except when accessing optical drive or similar and intake fans are SlipStreams running at 900rpm.
F-version removes push-pull fan config around HDD cage and has rubber strip between front and door's edge (leaving holes in door's side for airflow) but has 14cm intake fans so it should be about similar.