Asus Rampage 2 Extreme with Corsair Dominator GT

Hello,
I am currently building a new pc and have decided to use an Intel Core i7-950 CPU, with an Asus Rampage II Extreme Motherboard. My intention is to put 12GB of RAM in this rig. Asus lists as compatible only the xms3 range from corsair. However, this is a mid range IC at best. I would much prefer to put the dominator series or better, to take advantage of their better cooling, and more importantly the 1866Mhz speed.

Today, i went to the store where i buy my stuff from and they suggested i use two sets of the Dominator GT model with timings 7-8-7-20 (3x2GB) (part number: CMG6GX3M3A1866C7) making a total of 12GB. They also told me that they have built a number of systems with i7 950 and rampage 2 extreme with this RAM and that it is stable at 1866MHz. Is this the case or do you think they are just saying that so that i buy the more expensive product?
Suggestions?

Thanks.

P.S. My intention is to have 12gb of ram, being stable at least at 1600Mhz, preferably at 1866

Why do you need high memory bandwidth?

If you have a specific application in mind, great. Otherwise, that's one hell of a waste of money (as is the i7-950 - get the 920 and overclock it).

I have a similar build going here:

http://www.tomshardware.com/forum/ [...] d#t1984501

None of the hi end memory are on Asus's QVL for the R2E. I am planning to go with the Mushkin 99692's w/ 6-7-6-18 @ DDR 1600. They have equipped with "Ascent eVCI technology for enhanced cooling" which makes them a bit wider and Mushkin advises that they are not designed for (read won't fit in) 6 module installations. However some users report (see newegg reviews) that they fit just fine. If fit is tight, the Mushkin 99691's are designed for 6 module installations and have the same CAS 6 (6-7-6-18) timings

http://www.newegg.com/Product/Prod [...] 967&name=6

I am going to start w/ 3 modules as I don't run anything that can even approach 6 GB's of memory. If at some point in the future, I can take advantage of additional memory, I can add it then when undoubtedly it will be much cheaper.

In addition, everything I have read says that the $280 920 will OC as high as the $560 950 thereby "wasting" $280. It's still bouncing around my mind tho, that a chip which passes Intel's 950 testing must have more headroom than one which was derated to a 920. I see many people using a 150% OC at 4.00 GHz on the 920 though for reliability and longevity purposes,
I'd like to limit it to 137.5% where voltage adjustments either don't need to be made or are minimal. If one could clock the 950 to 4.2 and not need significant voltage adjustments, that would make spending the extra $280 more attractive top me but as yet, there's very little info available on OC'ing the 950 as everyone's opting for the 920.

If you decide to go with 3 modules (for now) or the 920, that would give ya well more than enough to offset the cost of higher quality RAM.