I connect case fans to the motherboard and set them to standard profile via BIOS.
CPU Fan is set to Silent profile via BIOS too.
Ok: generally speaking your current setup seems to me well balanced (maybe the 4870 is outdated and underperforming nowadays for its thermal envelope: you may think whether or not swapping it for something better from a performance/efficiency standpoint, and you may easily reuse your very good GPU cooler) with some remarks. EDIT:
First of all, as already noted, your PSU isn't a silence-oriented one. You do need a quiet one in the 200-300W range.
PSU's acoustic performance tested by SPCR out of the hotbox in the last months
MODEL 90 150 200 250 300 400 500
AX-850 <10 <10 <10 11~13 12 13 17
GX-700 15 15 15 17 21 25 35
TP-750 12 12 12 14 15 27 31
X-400FL <10 <10 <10 <10 <10 <10 <10*
MODU87+ 11 11 11 11 11 11 18
NX5000 11 11 12 12 12.5 14 19
ECO80+ <11 <11 12 16 20 23 28
X-650 <10 <10 <10 <10 <10 16 27
CP-850 12 12 12 12 12 14 20
* = overload
It would be a worthy investment if you could resell your current PSU, IMO.
Probably I would also use a less aggressive profile for the case fans too, and/or use a software like SpeedFan to have a somehow greater flexibility.
At anyway, IMO more probably that not you don't need the intake fan, providing that your 4870 already has its one.
Disconnecting the intake fan you might observe a marginal temp increase, but nothing serious (providing that GPU's VRM are adequately cooled by specific heatsinks).
Eliminating the intake fan you could get a noticeable improvement, as it's on the more straight path to your ears.
On the other hand the Fractal stock fans are already very quiet, so you might also not observe such an effect.
You have just to try whether or not it may be effective.
Even about the 7200, as already said, you can get rid of it, swapping for an SSD (or two small one, like some Intel 40GB, in RAID 0) and gain substantial improvement about actual noise profile (not to mention the increased performance).
Along with it, maybe you could/should swap your AC Freezer Extreme: it's a rather inefficient design, and moreover and it's a bit noisier than necessary at any speed above 800rpm. Otherwise, according to SPCR, its tonal quality is excellent.
Personally I would change it, but I think it's maybe a relatively new purchase, isn't it?
Here you can see SPCR findings about it (take note of the original fan levels): http://www.silentpcreview.com/article1128-page6.html
Here you can see how it compares against other coolers (from a silence perspective): http://www.silentpcreview.com/article1128-page7.html
IMHO it's not on par with your other components (always from a silence perspective).
Just FYI, I've recently bought a Cooler Master Hyper 212+ from ePrice at 24 euros, it may worth a look (but as for the AC itself, even that CM deserves a new fan, IMO, to fully exploit its quietness potential). Or a Scythe Mugen 2 Rev. B, I've found it as low as 40 euros.