Matching Different Types of RAM and Gigabyte MOBO Form Factor

Okay, I'm new here, so please forgive and inform me if I mess up some of the basic rules.

First off, I have built my own system from the ground up over the last several months. My hardware is listed in my profile, but I can list it again if it is necessary. Specifically, my problem lies within the usage of RAM in my system. I have a Gigabye GA-990FXA-UD3 Mobo that is DDR3 capable and has 4 RAM slots. I have 2x4GB DDR3 1333Mhz Crucial Ballistix Sport RAM sticks. I also have 2x2GB DDR3 1333Mhz Micron Technology sticks.

I have my system running stable at a 3.9 overclock on my CPU that runs at 50-52C under full load with Prime95 after 2 hours and 0 errors. (AMD Phenom II X4 Black Edition). Using my BIOS to overclock, I raised the multiplier to x18, and the FSB to 217, for a total of 3,906Mhz. When I did this, my other components automatically overclocked as well. Changing the multiplier did nothing, but raising the FSB changed all of the other values. For example, my RAM is running at 1430Mhz or so, my NB is at 2170, and so is my HTT. Also, the VCore has changed by itself to 1.42V or so, and I am assuming my other components have seen increases as well. I have manually changed the DRAM timings to 1T-9-9-9-24, I manually upped the the 1T Command from the 2T standard for my Ballistix RAM, and the new timings are even tighter than standard for the Micron. I just ran Memtest86+ through 2 full passes in 3 hours and had 0 errors.

My question is, am I hurting myself by running different types of RAM and at speeds other than recommended? With over 12G's I'm getting 7.5 Memory rating in Windows Experience Index. My temps seem fine after a lot of work with the fans and CPU cooler. The NB gets the hottest at about 60-62C at the very most.

Really, my question is two parted. First, why is it, and is it bad, that the RAM clock speed changes with my CPU FSB speed? My second question, is much more complicated. My Mobo has a strange RAM layout, I believe. It has 4 adjacent, identical slots. None are directly labelled. Above the top 2 slots, the ones closest to the CPU, is (approximately) the writing "Slot_2" above the word "Slot_4". Below the other 2 slots is the writing "Slot_1" stacked above the word "Slot_3". When I first installed my RAM on this build, I put the 2 Crucial sticks together in the slots farthest from the CPU (slots 1+3 here), and I put the 2 Micron sticks together closest to the CPU (2+4). When I look at CPU-Z. it says:

RAM : 12288 MB DDR3 Dual Channel
RAM Speed : 723.3 MHz (3:10) @ 9-9-9-24
Slot 1 : 2048MB (10700)
Slot 1 Manufacturer : Micron Technology
Slot 2 : 4096MB (10700)
Slot 2 Manufacturer : Crucial Technology
Slot 3 : 2048MB (10700)
Slot 3 Manufacturer : Micron Technology
Slot 4 : 4096MB (10700)
Slot 4 Manufacturer : Crucial Technology

Now why are they split up (the brands)? I read online that it is best to have the two largest and identical sticks together and the two smaller ones together, and they are, physically, but in my CPU-z it says they're split, and my weaker RAM is the #1 Position, the physical position of which is very confusing on the mobo. I tried to move the sticks around, but my system won't even power on unless they're in this EXACT physical set up that I started with and described above. Is this causing me performance issues? I want MAXIMUM performance possible, and I want to make sure my RAM isn't hindering me, as I'll be upgrading my CPU here very soon, after I sell my old 560Ti. I need to say, I have never had a BSOD with this current set up, and never experienced lag or any sort of freezing or overheating, so this isn't exactly an emergency. Overclocking at first gave me a few BSOD, and games quit randomly, but I haven't had those problems in a month and a half or so (on a two month old hardware set-up), or most of the time it has been running.

Please help me to optimize this, and if it's a problem, to fix it!

Thanks!