And if you spend tons in water cooling you can run it at 4.3ghz like me ^^ Of course thats pointless for Crysis but I do play other games where it is useful ^^ i920 is overclocking madness XD
why waste tons on overclocking, besides when overclocking this far the only things that needs this kind of speeds are the wii/p2 emulators and rendering/encoding programs.

http://valid.canardpc.com/show_oc.php?id=1260963
i5 750 oc using a corsair h50 cooler.
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115215&cm_re=i5_750-_-19-115-215-_-Product
http://www.newegg.com/Product/Product.aspx?Item=N82E16835181010&Tpk=corsair%20h50
that's $79.99 + $199.99 = ~279$
less then the 6 core AMD but with much more processing power.
And considering that the ram and motherboard you've chosen is way better then mine you should have no problem reaching a higher overclock if you get a better water cooling then me.
the H50 I've chosen cools slightly under the top air coolers. But as a bonus i don't have to put a friggin huge 1kg fan on top of my CPU.
I did it because I can? Becuase I wanted to? Not everyone wants a slow ass PC.....
You don't have to spend tons on watercooling to get it that high, I just did becuase I wanted to push it to the limit, and unluckily for me, even with the good stepping, my CPU sucksss. There is no way MY cpu would go that high on cheap watercooling or air, while others haVe got theirs higher on just air. It's down to luck of the draw with intel CPUs...
And any game that is heavily demanding on the CPU DOES benifit from it! Other than Crysis I have yet to find a game I cannot max settings and run at 1900x1200 and get smooth as silk FPS. Games like Arma2 is heaily demanding on your CPU where a faster CPU does help. Also any RTS game where there are hunderds and hundreds of units on the screen at once, can get very CPU demanding. COH for example is CPU hogger when you are playing with 5 CPU and yourself!. That's not to say having a £500 GPU isn't more important mind you, but there is no point having one without the other.
Anyway back on subject, You can buy any cheaper i7 etc and just overclock it to just over 3ghz easily, even with stock heat sink (Not reccommended but possible) saving your self hundreds and hundreds of pounds for a few hours work. Basicallly and not trying to be horrible here, only lazy people buy the stupidly expencive alredy high clocked CPU, with more money than sence XD And I used to be just like that, but I changed!
Google is your friends, read up on it, and you will relise it's maybe not as hard as you thought.
Oh any my GPU is pretty loud, alas super powerful GPU do get loud when stressed....However I have read that the new Nvidia graphic cards they have just released are super quiet, so if you want a dead quiet GPU I would concider those.