Here's my temps after installing a Noctua U14S heatsink, and replacing the exhaust fan with a Noctua 140mm 3000rpm industrial fan (running at 1500rpm). Good, but probably typical. Ambient at max was about 80f. The low temps are morning temps, it was about 16c. Still virtually silent at all times.
I really have to say, anyone would do good to at least replace the stock exhaust fan....it's supposed to be quiet, and it's a good fan, but 1000rpm isn't enough and it has a really low exhaust CFM, lower than rated, especially since that rating is without obstructions like the hexagrill on the exhaust panel. If you can't feel an exhaust fan moving air, it's not going to work well. Before, I would just feel heat slowly creeping out like an oven, now I can feel a strong breeze coming out the back. Since the Noctua is a high static pressure fan, it's going to draw air into the case as well as exhaust it, making the weak 90mm 30cfm fans in the front less consequential, along with the static pressure helping to draw air through obstructions of flow in the case.
Good thing I took these pictures, my left front fan was being blocked by a SATA power wire that got loose! So those temps were actually with just one of the 90mm fans working. I doubt the temps would change even if I turned off both intake fans, because they're pretty weak. My exhaust is definitely pulling in more air than they are. I think the stock fans are the only downside to the case.
I turned the drives backwards in the cages to make sure there weren't any issues with the cooler fan. As you can see, there's a good deal of clearance for the cooler fan....about as much space as the upper crossbar in the middle of the case.
My initial worry of the U14S was if it would come too close to the GPU backside, and thankfully it has plenty of room.
It's a little cramped, but that really just means less volume for the high static pressure exhaust fan to suction out. Hard to change the clutter with all the non modular wires. Doesn't have to be pretty inside though, just has to perform. Since I'm using only 2.5 inch drives in the drive bays, there's plenty of room for airflow to the cooler.
I personally don't think two fans are needed, not with the distance between the heatsink and the exhaust fan. The exhaust is powerful enough to quickly move any air coming from the heatsink, along with pulling air from around the sides of the heatsink. I chose it mainly because it can move more air than both the heatsink fan and intake fans combined, along with creating its own pull. That means even if there are obstructions within the case, the exhaust will still be able to pull air out faster than it's coming in. If I had a smoke machine, you'd just see air effortlessly and quickly flowing through the case.Edited by AMDATI - 6/24/16 at 9:58pm