If a HSF that blows towards the back exhaust fan is used, and the back exhaust fan is left on, then you have much of the push/pull effect of duct + dual 120mm fan setup. While the incoming air to the CPU HS might not be as cool as if the duct was used (it might come across the RAM only...), the pressure and air velocity across the fins would benefit from the close placement of the HS fan and so compensate for the absence of the duct.
This might cause more of the CPU heat to rise up into the rest of the case, but with the HS fan and back 120mm exhaust fan working in tandem, it probably would be a very small -- if any -- thermal change. There would also be the added benefit of the incoming 120mm fan airflow now spreading throughout the case rather than just through the duct.
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The possible restriction of the bezel drill was noted in the review. However, for the sake of curiosity, I studied the bezel very closely this morn.
The blade area of a 120mm fan with a 45mm hub (typical; applies to Silverstone fan) is 8777 sq mm.
The blade area of a 80mm fan with a 35mm hub (typical; applies to Silverstone fan) is 3612 sq mm.
Therefore the total intake area need to feed these fans without restriction is 12,389 sq mm.
The front bezel has 120 holes measuring around 3.5 x 23 mm. This results in about 9660 sq mm. However, the metal dust filter behind it is a simple pattern of small round holes with more metal around each hole than is ideal. I would estimate that the amount of restriction represented by this filter is at least 30%, maybe as high as 40%. This suggests that the total intake area is 7000 sq mm or less. It is perhaps 40% shy of the area needed for unrestricted airflow.
Then you have to add into the equation the small amount of grillwork that's directly in front of each fan. These are very minimal and subjectively don't really restrict the airflow, but it's probably another 10% -- 1240 sq mm.
So now we are down to half the intake area needed to feed the intake fans without restriction.
The question is what impact this has.
1) Does it mean the fans deliver less than "free air rated airflow"? Yes. But how much less is hard to tell, this will depend on rpm. (pressure changes with rpm)
2) Does it mean air has to accelerate through the openings to get enough volume? Yes, at higher velocity, this is what happens, and the additional turbulence results in both increased noise and decreased airflow. Again, how great this effect is depends.
So Bluefront, your instinct about the front bezel appears correct. It is probably too restrictive.
The test rig at SPCR has long been dismantled, and there are other reviews in progress, so it's not available for more experimentation. But members who use this case could report on the result of this little experiment:
Record all the temps as best as you can after running full load (CPUBUrn or full system benchmarks) for at least 15-20 mins. Then open the bezel, remove the metal perforated filter behind the bezel (just need to undo a few screws), close it up and repeat the system stress exactly. After the same amount of time, record the temps.
That screen represents at least 30% restriction. In theory, removing it should improve all the temps at least a little.
EDIT: BTW -- the simple expedient of removing any of the exposed front drive bay covers increases the intake area to the front fans -- there is a 3/4" gap between the front bezel and the chassis front panel where the fans are mounted. So removing one or both floppy drive covers should have a noticeable cooling effect as well.
The metal screen removal, a floppy door removal (maybe stick the metal screen up there instead?), cutting away the inside fan grills (not needed for EMI anyway because of the front bezel) and then applying a better dust filter directly in front of the two fans would probably make the intake as unrestricted as it needs to be.
Alternatively you could cut out the bottom lip that's part of the frame between the front bezel "door" and the front steel panel. This is pretty thick, but it is aluminum...
processor, but it's what I've got, so I have to do the best I can with this as a starting place.
