All oversized coolers are in the same rough ball park for cooling, the difference between them is mostly aesthetic or acustic in nature.
The Noctua cooler WILL mess with your vengeance ram coolers, so I would look for a cooler that fits in the normal CPU area.
Personally I use a hyper 212Evo with 2 800rpm fans (stock fan was a bit loud for my tastes). At 4.1GHz under load (as far as I can go as I do not have a K processor) I am hitting temps in the high 30's, with a max temp of 41*c. With daily use it stays in the high 20s to mid 30s, and idle is at 23*c. Very acceptable temps and I am sure it is just as quiet as the Noctua at a much lower price.
If you want something better then look into Zalman. My old Zalman cooler was extremely quiet, and kept temps very cool without breaking the bank, and looked way better than the 212evo (only got rid of it to put it in my wife's case as she was having a heat problem because her case does not breathe well).
This is the updated version of what I had (except mine did not have the blue fan) http://www.newegg.com/Product/Product.aspx?Item=N82E168...
There was a little bit of fan noise, but it was very low wind noise and not coil whine so it was barely noticeable. The 120mm version would be quieter.
Whether it blocks it will vary between motherboards and where the memory slots are located. On my ASUS, slots 2 and 4 will clear the CPU cooler (I'm using the hyper 212) completely, so the height of the memory doesn't even matter. You'll either need someone with the same mobo as you to confirm if that's also true for you, or get the dimensions of the CPU cooler and get in there and measure.