I think it's better if you install the fan normally, then change that top exhaust fan on the Antec 900 into a top intake fan. I read it somewhere before, and that actually generated more cool air into the case, thus significantly lowering the temperatures.
I have the cm 690, and 7 fans, i have my fan facing towardsthe dvd drive though i see some people have their facing towards the video card, i wonder should i turn mine around ?