Here's my latest try at silence, based on the thought that total power load should be equally divided between PSU fan and case fan.
Alas, the case is ducted/divided so PSU takes its own load plus the CPU, and the case fan takes HDD:s plus graphics.
In this setup I have put the 120 mm fans in the PSU and case on constant low speed, and the two 80 mm fans for CPU and graphics are variated via Speedfan.
There's a divider from the ODD cage, slightly down, then lining up with the uppermost PCI slot in the back. Some cabling has to go through this divider, as well as the RAM sticks.
The bottom case fan blows inward across the HDD:s (in stretch bands), there's a little divider here as well to direct flow to HDD:s.
Here you can see the front intake through an open cover in the ODD bay.
No air is at this point filtered, not sure how to attain that for the upper part. (Used to have filters on bottom fans).
Temps for : idle / 20 min of Furmark
Ambient 24 / 24 C
Case (MB) 33 / 40 C
PCI (Outlet) 28 / 37 C
PSU outlet 35 / 44 C
CPU 52 / 69 C
HDD 28 / 28 C
The bottom inlet fan works wonders for HDD temps.
PSU fan should probably also be variated, or set a bit higher (CPU temp @ 69 is not that good, but the 80 mm fans were still drowned out by the 120 mm fans @ low, even when ramped up).
Also tried a setup where the PSU fan was variated, and the CPU fan at constant low - roughly the same figures came out, but at higher noise levels.
Putting the CPU fan @ zero made the PSU fan ramp up even on idle, so semi-passive seems not work, unless i duct the HS and/or get a larger one (Ninja e.g.).