and mainly is there some way to lower the cost by changing something keeping in mind quietness & performance as i ended up 100€ above ideal budget?
We need more info before we can really help you cut costs. Also, it is hard to know Euro availability of parts as sites know we are searching from the USA.
First, we need to know what resolution your screen is, and at what resolution you would like to run your games. This is important in choosing a video card, and video cards decide how much power and cooling the computer needs. If you are running 1680x1050 or less, you could use a passive AMD HD 5670 with 512Mb of GDDR5 saving noise and 60€.
Next, we need to know how willing you are to trade lower cost for lower performance.
If you dropped the i3-2100 and used a Pentium Dual-Core G840, you would save 30€. The dual-core CPU will not need as much cooling as the quad-core, so I expect that you could save 15€ on cooling (Scythe mugen 2 replaced with Xigmatek Gaia). (45€ together)
If you dropped the 7200 rpm drive and bought a 5400 rpm drive, you could save 15€. You could then also drop the HDD Silencer, saving 22€. (37€ together)
Also, You have an old DVD drive but you don't list what your other "old" components are. If any of them are usable, you could save the needed 100€ by pulling parts from the old system and putting them in the new system. Just re-using your case could save the 100€.