Originally Posted by Mister B
Hey Trelga, it's not recommended to have the rear 120mm fan as an intake fan as GPU's generally tend to exhaust out towards the back, as do some PSU's. I have the H100 fans set up exhausting out the top and the 120mm out the back and it's fine.
I swapped out the 200mm front intake fan from the 650D cause that thing was 747 loud! I now have a Bitfenix Spectre Pro instead, which just barely fits. I would've liked a better 200mm but because there is only just about 25mm spacing, a 200mm x 30mm fan was out of the question if you wish to have both hard drive cages in their stock positions.
As for 140mm instead of 200mm. I guess with some light modding to the mesh of the front panel you could fit a 140mm in. I doubt two would be an easy fix though.
Actually, you can install a 30mm fan. I had a 200mm x 30mm 166 cfm NZXT fan installed in my 600T, which has the same measurements at the front and the same drive cages as the 650D. It requires you to cut the curl off of the drive cage in the front left corner, both if you need both cages. Once you do that, a 30mm thick fan will fit in with the same snugness as the Spectre Pro fits with unmodified cages. Unfortunately, I don't think the screw holes line up though (I have the original 600T with the brackets instead of screw holes). I got the top two to line up in the mesh, and I just let the bottom of the drive cage hold the bottom of the fan against the mesh. Incidentally, in this particular revision of t he 600T, the SP 200mm doesn't fit either since there are no screw holes. I lined up the top holes with the mesh as I did with the NZXT, and I used cable ties on the bottom going through the bracket holes.
I just installed a Spectre Pro because it's a little quieter. Now that I've been using it, it is really not even close to as good as the NZXT fan was at full speed, but it is way quieter. (The NZXT fan was so strong at full speed, if I slowly moved the front dust cover closer and closer to the case, at about an inch the pressure from the fan would suck the dust cover closed).