I would say that without a duct the psu will quickly ramp up. I experienced this problem even though I used a front fan psu.
That's what I feared...
A duct worked well for the cpu & psu but not for the graphics card (the cpu monopolised the exhaust).
I'll see what the HR-03 and two intake fans can do about the GPU...
With a top facing fan psu it was even worse as adding a duct created turbulance noise.
I was indeed afraid of turbulence because of the vicinity of the PSU fan and a CPU/exhaust fan air duct...
I think the best solution is to put the psu in the bottom (antec p180 / lian li 1000).
That's unfortunately out of the question, since I've already ordered my Solo... Anyway, I litteraly fell in love with this case ^^
I wouldn`t worry so much about the heatsink fans though. In my dumped case at least they are drawn out by the intake & exhaust fans. And still, the sum of their noise is less loud then a soft mounted, 2,5 hard drive sandwiched between 2 incactive ones. This is just from my experience, but it makes me think it`s better focusing on other parts first if you seek silence.
Yeah, I think you're definitely right. Anyway, I'll give my project a try, and see what SpeedFan says about my temps. If it gets too hot, I'll just add two silent fans on my heatsinks, and I probably won't notice the difference. As I was saying, I'm just very seduced by the idea of cooling the TDP-Monster that I own with just three case fans (and a PSU). But that definitely sounds too dangerous and, because of the PSU fan ramping up, even much noisier