Upgrading RAM?

[cctaylor88]

So I will be running two seperate kits of ram and I was wondering if everything would be compatible as well as run at full capacity/potential. I currently have in my computer 2x2gb planks of g.skill ram (I will provide links below) and just purchased 2x4gb planks of g.skill ram that will soon arrive, now I noticed on my motherboard that there are a total of 4 slots for planks of ram and they alternate color from left to right. I assume I should put the same sized plank of ram in every other slot (as to coordinate same ram in same ram color cradle on the motherboard) is this correct? If so, why is my motherboard like that? Is this what you consider "dual-channel"
1)Will my 4 total planks of ram (2x2gb and 2x4gb) all be compatible and run well or should I just run the 2 planks of 4gb?
2)Should I place my planks of ram in every other slot so that the same size ram is in the same colored cradles? Also, why is this?
3)And finally does it matter which set of cradles I put the 2/4gb sticks in? As in should the higher ram be in the black or blue cradles?
Both sets of ram are from the same manufacturer, both ddr3 1660, same CL, same 1.5v, and same timing except the 2x2gb have a "-2N" at the end (you can see on the newegg link) what does the 2N mean? 9-9-9-24-2N
My motherboard: AMD Phenom II x4 955
My current ram-2gb: 2x2gb
Ram purchased-8gb: 2x4gb

Also, I have heard varying details on how I should place the ram on the mobo...some say I should make sure each channel has equal amounts of ram so it would be 2gb+4gb in one channel and 2gb+4gb in another channel, seperating the ram. I always thought you should keep ram kits together?

 

[cctaylor88]

EDIT: The above should be 2x4gb

 

[Blastman]

This Intel memory support article explains how to populate the memory slots to run dual channel mode with different size modules.

1)Will my 4 total planks of ram (2x2gb and 2x4gb) all be compatible and run well or should I just run the 2 planks of 4gb?

All the memory will be compatible. You can run all 12GB in dual channel mode. The timings will be set at the timings of the slowest modules.

2)Should I place my planks of ram in every other slot so that the same size ram is in the same colored cradles? Also, why is this?

Basically, the 2x2GB modules go in the same color slots, as do the 2x4GB modules. So you get 12GB running in dual channel mode.

Rules to enable dual-channel mode
To achieve dual-channel mode, the following conditions must be met:
- Same memory size (1 GB, 2 GB, 4 GB, etc.)
- Matched DIMM configuration in each channel
- Matched in symmetrical memory slots
Configurations that do not match the above conditions will revert to single-channel mode. The following conditions do not need to be met:
- Same brand
- Same timing specifications
- Same speed (MHz)
Memory channel speed is decided by the slowest DIMM module populated in the system.

3)And finally does it matter which set of cradles I put the 2/4gb sticks in? As in should the higher ram be in the black or blue cradles?

No. Each set (2x2gb and 2x4gb) can be used in either the black or blue slots.