Ganged or Unganged

There's a lot of info on this on the web. This is specific to AMD CPUs. I only use Intel CPUs and they generally recommend using dual channel mode. The bottom line: try it both ways and see which works best for you.

Web Info:
Ganging is AMD's version of Nvidia's Locked vs unlocked architecture basically allowing you to use your ram in dual channel vs single channel.

Ganged = dual channel mode for ram. All cores get access to 100% of the ram.
Unganged = single channel. Each core gets access to a stick of ram.

The Phenom processors work a little differently than most other processors when it comes to the traditional thinking about dual channel memory operation. Phenoms have dual, or 2 memory controllers.  Each controller can wor independently from the other and run a bank of memory in unganged mode, bandwidth. In the ganged mode you lock both banks of memory together, 128 bit bandwidth, but only 1 controller can be used at a time, 1 must wait on the other to finish what it is doing. There is more bandwidth this way, but most people don't need it, and running your memory in unganged mode, allowing the controllers to work separately will result in better performance. Gaming is one area that shows a significant benefit by leaving your memory in unganged mode. Unganged mode is the default mode for Phenom processors.