For a gaming rig, you will never need more than 8GB, not anytime soon anyway. But get 16GB if your heart is set on it. 32GB is just utterly ridiculous, even purpose editing rigs don't peak at using that much. Business Server PC's or heavy Program Development PC's (Like I assume Mindless' is) which needs to run a ton of stuff all at once may need that much (Though I think for large business servers, they use blades of 1TB of RAM)
You might as well use the Dual Channel, I cant tell you how much better it performs, but I know it does. If you were to disable dual channel and compare 2 vs 4 sticks of the same specs and total capacity, there would be no difference (except maybe in energy consumption).
If im never going to need more than 16gb i'll just get the 4 x 4gb sticks, its easier to replace one of them if one of them manages to pack in for whatever reason. It looks better filling up the motherboard too im getting the one below
I just had a idea. Take a look at the picture in the link below, the setup on the bottom is what i was going to get but i changed the i7 3770k to the new i5 3570k after reading that the i7 offers hardly any difference in gaming for the extra £100.
You can see that i've managed to get the asus maximus motherboard on there and let it still come out £20 cheaper. The priority turn around costs £45 on the quotes i have there. The HDDs will be set to raid 0 but i need to specifically ask for that to be done, its a bit wiered it doesnt give me an option for that.
I agree with the fact 8 gb is more than enough. I have an AMD Athlon quad and a board that takes ddr2. I used to have 4 gb installed, but ended up getting a couple of 1gb sticks for free that were the same speed as my old sticks, so I'm running 6gb right now with my quad core, and even when playing Crysis 2, I still have at least like 2 gb free on Windows 7 64 bit. So for gaming, wouldn't worry about more than 8 right now.