Then with my actual configuration the E9 400W would be a good solution, right?
Yes, as I've already said a couple of posts ago, the E9-series is a good option (for the proposed rig): but if you go with the R4 case, check the PSU 8pin CPU power cable length, before buying both.
I am really new to the idea of buying a quiet or silent pc so I'm still gathering informations. I have also been more focused on minimize the noise from the fans, I'm aware that the Hdd is one of the noisiest component in a pc but I haven't read anything specific yet. I really appreciate your help in these matters.
The shop where I am buying is qmaxtech.it and I'd prefer to buy here because the prices are lower than almost every other shop in Italy but especially because I have never assembled a PC myself and they can assemble a pc for you. Since you are italian can you suggest me some other sites where I can buy components with low prices?
If I were you (and I am not), I would use a somewhat different approach, starting from a basic concept: noise and performance are somehow antithetical requirements, and any cost always increases, if you want more quietness. Just a straight example: an average user would choose an hard disk drive relying on the basic parameters of capacity and speed. When I need a drive, I want it quiet: so at first I look to any suitable 5400rpm 2.5" drive (7200rpm ones are always audible due to the airborne noise), encapsulated in a Scythe enclosure (a QuietDrive or an Himuro), and then suspended with a Noise Magic NoVibes suspension system, softly mounted into a 5.25" bay (so I will look to a case which can have some convenient, solid 5.25" bays, and not for one with the more usual and blingy tool-less 3.5" removable trays).
This approach would lead to some constraints about the choice of the case, and to an increase of the overall cost of at least 30-40 euros with reference to the bare disk. If I should need a somewhat more performing disk (a 5400rpm 2.5" is sub-par), I would look for any higher than needed capacity, short stroked, suitable 3.5" 5400/5900 rpm drive, suspended in a NoVibes cage, and this would led again to an increase in costs of at least 30-40 euros (over a bare 7200rpm hard disk).
But in either way, my peace of mind (and ears) comes definitely first.
Well, first of all, for a gaming rig I would start from your monitor resolution, as it's quite a different path building a rig for any "Full-HD" or above unit (or for a multi-monitor setup), which usually requires the most powerful graphic card you can afford, rather than for any "HD-ready-like" (1680x1050, 1600x900, 1440x900, 1360x768 and lower) one, which usually doesn't need such a card.
So, to spend more on the GPU, or more on the CPU, mostly depends on that (and therefore, currently, the choice between AMD and Intel, as using lower resolutions monitors calls for an Intel, IMHO); it's also worth to mention that opting for a mid-class GPU (and a rather powerful CPU) could let you shrink more likely the form factor, if that were possible and desired.
Anyway, whether financial concerns stood above any performance ones, as a very personal feeling, maybe an ASRock Z87 board mated with am Intel Pentium G3420 or G3430 CPU could turn out to be an interesting viable alternative for a budget gaming system, over the proposed FX4300 combo.
This preliminary decision will let you to estimate also your power and thermal requirements (today a GPU usually draws more electrical power than a CPU): and these latter will lead to the choices of PSU and enclosure. The inner, intrinsic quality of these two components IMHO should be as high as possible, as reliability and noise noticeably depends on that (not to mention you can upgrade the hardware but re-use case and PSU, if they are of an high quality): so it's not excessive to think about investing around 30% of the whole budget on these two parts, IMHO.
If a PSU is relatively straightforward to choose (a unit which matches the power requirements, which has a favourable noise profile within the intended power envelope, and eventually which fits the actual budget), choosing the enclosure may be a bit more tricky: a gamer case demands for GPU cooling, so it's usually wide open, with lots of intakes from which noise escapes, and lots of fans which make noise.
A quiet case is quite the opposite: doors, hinges, almost no intakes, heavy panels, very poor cooling, all to trap the noise inside.
But a too much low airflow could likely lead to an increased GPU fan speed, defeating the purposes for which you've chosen such an enclosure...
...to be practical without being hasty, the proposed R4 is one of the best "quiet", reasonably sized and reasonably priced, ATX mid-tower cases available, so, providing you will properly drive its fans, no question about (any hardware inside would run hotter than necessary, as in any "quiet" enclosure).
Then I would look to my favourite games, or the ones I would buy/lend near in the future: some titles are AMD-bound, other ones are Nvidia-friendly, but there are also very popular games which don't demand a very powerful graphic card.
So you do need to perform some web searches, looking for any reviews which use those games to benchmark the various videocards (up to now it seems to me that someone just told you that the 7790 *is* the card you need, and no more), in order to try to identify which architecture (GeForce vs. Radeon), and which performance class (to say: a typical 7790 is way less performing than any R9 270X, but more than a typical GTX-650Ti, and so on) may be suitable for your gaming requirements. When you got at least a couple of viable alternatives, some more specific, noise related considerations (as the availability of a particularly quiet model) may then alter the above mentioned performance-based findings.
Summarizing, this second-level analysis should tell you whether or not (and, in case, how) to change any previous made budget allocations (on CPU, GPU and case).
Just then I would start to select the actual, specific parts, looking for some alternatives for each component (namely two or three, maybe four, but no more).
If about CPU and GPU you should deal mostly with raw power and games requirements, motherboard is a different thing: a typical budget-conscious gamer would look for an essential mobo, with a good/reliable onboard cooling, a solid power circuitry, and maybe some fancies for overclocking. Otherwise a "silencer" should look for a sophisticated bios, with an high number of software controllable fan headers (which have to match the number and type of the available fans), and possibly some form of undervolting. Sometimes noise-wise the need for some specific motherboard features could led to change the hw architecture (Intel over AMD, FM2+ over Am3+, 1150 over 2011, or viceversa).
The proposed M5A97 is a basic model, with no particular attractions/special features either for a silencer, or for you: it looks like a solid board, but it lacks programmable 3pin fan headers (the newer R2.0 version offers one more 4pin fan header, so this latter could be preferable but not mandatory, IMO, as your proposed rig doesn't have PWM case fans, and moreover the R4 sports aboard a fan controller, which may prove to suffice).
Broadly speaking, in order to do your homework, you'd have to check online manuals, comparison tools and some trusted reviews to evaluate the various boards (while Intel, ASUS, MSI and ASRock are often regarded as the more silencer-friendly brands right now).
So, these proceedings leads me to say that tendentially I would not buy parts where they cost less, but where they have the ones I need: just at the end of such an identification process, I would try to maximize the purchases at the more affordable stores (as they may not have the right components).
Ending with qmaxtech, personally I've never bought from them, but I have friends which regard that shop as a serious one (just I would never let my system built by a third person, even if it were my first build, because only me know what I really want: but luckily you're not me, and above all I understand your worries, such as what to do, if it shouldn't power up properly, when you turned it on for the very first time).
Take also note that, if qmaxtech were a painstaking seller, then they should not mount the HR-02 Macho on your system (as it's rather risky to ship such a cooler bolted to the mainboard), so that one of the probably most difficult tasks - when building a PC - should still remain up to you.
For any alternative to qmaxtech.it, price-wise, IMHO there could be so many (such as planethardware.eu, bpm power, and so on), that's nearly impossible to me to conveniently/effectively summarize: I usually rely upon price comparators. I'm used to check prices at the same time at least on trovaprezzi/shoppydoo, twenga.it and Google Shopping (take note that they do not always carry all the available offers), and very often I also check prices on several Amazon european sites (if you can pay by a credit card, and you're not worried about ordering in different languages).
Yes, I know, it's a time consuming attitude...
Actually I intend to buy the Thermalright macho so I think that the noise from the cpu will be lower than most of the other components.
If I buy the E9 instead of the XFX Pro and the caviar green/WD red instead of the caviar blue the noisiest component will now be the gpu?
Your mileage may vary (idiomatic expression, somewhat mistreated: read it as "potrebbe essere così, ma anche no"): I don't know that ASUS card, I can't help, I just can say that the ASUS DC-II cooler proved to be relatively noisy on the 7950, while being very quiet on several GTX like the 660, 660Ti, and 670 (but not so quiet on the 680).
And above all, up to now I still don't know whether or not, performance-wise, it's the right card for your gaming needs.
At any rate, according to TechPowerUp!, it should be a very quiet card (and if it were true, at least at idle the loudest parts could be... the 140mm fans! So, provide to drive them properly).