While yes, you can run 32GB in dual channel - the above info from Drtweak is wrong. Each channel is composed of two slots A1, A2 and B1, B2 - for full dual channel to work you need a like amount of DRAM in each channel (in his example you would actually be in flex mode with 8GB running dual and 4 running single channel mode), with his stick selection you would want a 4GB and a 2GB in each channel to have the 12GB total all running in dual.
Best to get a 4x8GB set, the data rate that you can run is determined by your CPU (in particular the individual MC (memory Controller)