I'm really confused about this topic now. I have the m4a785td-v with 4 slots.
Now I wanted to use the dual channel mode and installed 4 dimms, all are KVR1333D3N9 2G by Kingston. In total I've installed 8gb Ram, but I thought because of the dual channel use I will be able to use only 4gb. After I stared Windows 7, it tells me I have 8gb.
I haven't found an option in the bios to activate the dual channel use of the dimms. I really don't know why I have 8gb.
They have to be compatible, because they are identical.