Performance question regarding CPU + Ram channel

I believe the K suffix means its designed to be overclocked more,
I'm sure someone else will chip in with more detailed info tho mate,
Moto

K series denotes an unlocked multiplyer, making it overclockable. For a gaming machine you should be looking at the 2500K which is easily within your 300euro budget.

Where are you from, and what e retailers do you use ?

I'm from Greece and i haven't used any e retailers for computing stuff so far and i m not so sure if i should either...since i wanna make sure that the components arrive with all the default "box" parts. Anyway thanks for the comments so far...i m expecting some more elaborated info on the # channel RAM vs nm architecture as well.

With Intel's newest series of chips, ALL the buses are now on the CPU. Because the PCI and PCIe buses don't handle anything above 107 to 110MHz, thats the limit you can OC the buses now. Because of this Intel has started selling unlocked CPUs for the enthusiasts.

While memory bandwidth matters, the instructions per clock (IPC) matter more. It doesn't matter if chipset X has triple channel ram if CPU Y is faster clock for clock. As long as CPU Y has enough memory bandwidth it will be faster then anything chipset X can support. (clock speeds being equal.) Intels current clock speed king is the 2xxx series, so get one of them.

Edit: A good example of this is the Phenom II series vs the C2Qs. AMD had the more elegant memory design with the direct HT bus linking the cores directly to the ram while Intel still used the older and slower FSB. This didn't matter as the C2Q were still even or faster then their AMD counterparts.

Also i've considered the i5-2500K but vs the i7-2600K it lacks on # threads (actually has half) and it also doesn't support the Intel® Hyper-Threading Technology. Is it worth paying the extra buck (like 100 euros or so..) for these features?

For the most part I would argue no. Currently the 2500/K is already one of the fastest CPUs you can get. 4 threads is plenty for gaming, and the HT ability of the 2600 isn't going to get you much more most of the time. Unless you need the fastest, the 2500 is fine.