Hello , let me start by saying thanks for replying to all.
Now for the setup : Z68 SLI / i5 2500k + V8 CMasters / 2x 460 GTX FTW 
                               The small problem comes when selecting the RAM - I was going for either Corsair Vengeance @ 2133 or now that my fav. brand is back in the game I wanted to go for GEIL Corsa 2x4(x2) Dual Channel @ 2133 CL11. However after a chat I had the other day with a group of friends they basically told me not to buy memory @ 2133 Mhz because my 2500k won`t work / won`t be stable etc ...
 
Q&A: 1. Why?
         2. Would the Corsair Vengeance / Geil Corsa @ ???? Mhz would best fit into my rig 1600 Mhz ?
 
Thx all I think this about covers it . 

AzN-SoLjA

I would recommend the 1600Mhz memory. You will barely notice any difference from the higher speeds to day to day things and the fact you save some cash. I'd say get lower/faster CL timings instead of the slight faster speeds. I also hear 2133 is hard to get stable around here, like a hit or miss whether or not you'll have problems using them.

+1 2133 can be problematic (note here: ram is no longer affected by the mother board as it was in the past, it really depend on you cpu chip. its hit and miss.) since intel only says your chip is good to 1333 anything above that is technically overclocking and a bonus.
1600 is the most common selection and with the tons of benching i've done you will only see a very minor difference in speed. 1866 is a good option also and can be a good compromise.
as far as brand choice its really up to you these days they are all basically the same. pick the one that you like and is pretty.