The 3.6mm nozzle is the smallest one in the nozzle kit, thier for it creates a jet like stream that hits the copper plate on the D-Tek from the inside cooling it down better. Think of it like this. Say you have a shower head with multiple setting, setting 1 is a steady stream (Stock) setting 2 is a powerfull stream (5.5mm nozzle) and setting 3 is the more powerful setting with the 3.6mm nozzle. What happens is the hole where the coolent enters the block gets smaller I.E. the smaller the millimeters the more pressure, the higher the millimeter the less pressure, but all this comes at a price. The more pressure you use the less flow you get in your loop, and having a good pump can actually mean slowing it down. Which restricts the whole loop making temps higher than you expected, but you can try all the nozzles with the quad you'll be getting and see which one gves you better temps. Its trial and error when it comes to watercooling.
This link has the information you need to find out the Flow ristrictions of each nozzle
Check your motherboard. Look on the back of it, there should be a metal plate there. Some motherboards do not have this, while others do, but most high end motherboards do for the simple fact that it help support against warping due to clamping down heat sinks or water blocks. The back plate also have pins that come thru 4 holes for AMD, and 2/4 for Intel. The retention clip, the black plastic thing around the processor socket then gets screwed into that plate.
This is an Intel Backplate that came with my Case. I don't use it because I have an AMD, plus this thing is made of aluminum which is no good.
This is the Backplate that came with my mobo, which is made of steel, very strong
Here is another pic of the backplate, on a sheet of 8x11 paper just to give you an idea how big this is, but it seems odd because this thing isn't that strong. I could bend it if I wanted to easy, so it might not even be used for that purpose, infact I think it might be an adapter more so for the case. who know. But thats what one basically looks like. I'm not to sure but I think AMD mobo have back plates, while Intel don't in some cases but I could be wrong
Hope this helps you alittle bit better