Thanks for your input.
In previous messages, 28 Nov., xan_user has a similar one with one fan or a vertical airflow. Small case also.
Maybe it's sufficient.
Do you have a bigger CPU than i3?
Mine would not generate much heat.
IMHO Ivy Bridge and Haswell are indeed low power CPUs but they are also not so efficient at heat dissipating (unless you delid them), while the original Sandy Bridge (I've a 2500K and a G530) is usually clearly better.
Said that, I can't help: you have just to try whether or not it's enough (at least, this is what I would do: trying, and see what happens).
Maybe if it's not good, I can later add a case fan at 300rpm.
Usually in a low noise system a single exhaust should be preferred, but with reference to Lian-li Q27 and Cooltek/Rosewill enclosures I don't see where to put such a single large exhaust fan.
The original Lian-li Q07 looks like better to me, with reference to fan placement.
For the thermalright, did you have the HR-02?
It seems to be the best one with the Scythe Mugen 4. Recommended around here by several users.
I was talking just about the TY fans: I've several TR coolers, from the original HR01 up to the Archon SB-E X2, but I've not the HR02.
In my opinion the HR02 is a very good cooler in a low airflow environment (like your one), but if you look at xan's setup, more probably that not the typical HR02 orientation may not be optimal (I don't know if you can change it, I guess so), at least with the Q27 and Cooltek/Rosewill enclosures; on the contrary the TR TY fans are - IME - not so bad but also a bit far from the best available (noise wise several Phanteks, Noctua, Scythe, Corsair, Antec, Bitfenix, beQuiet, Noiseblocker fans should be preferred over them, IMO/IME).
I want to add that the behavior of any fan can not be treated separately from that of the controller to which it is connected, so YMMV (and as a matter of fact my TR TYs sound better on my Sandy Bridge platforms than on my AMD ones).
Broadly speaking, IME/IMHO 140mm fans are not the best sounding ones around: usually you can't lower their speed enough to see their sound signature disappear, and while at 400rpm a good 120mm fan is often unnoticeable, any 140mm fan at the same speed (there aren't so many who can go that low) is not. Unless you place the box not so close to your head (like a mid tower under the desk).
Take also note that when placed horizontally, very often a fan is more noticeable than when it's vertically bolted.
In my opinion something like a Q07 with a pair of vertically placed good 120mm fans (one on the heatsink, one on the case), running at no more than 300-350rpm, should be the best tradeoff achievable, and it can be (any vibration issue set aside) extremely quiet (at night I can hear distinctly an ~11dB Seagate GoFlex idling over such a dual-fan setup, standing no more than a foot from my nose).
But as I said just above, give a try to your ideas: it's almost always the better option.