Los chipsets modernos de intel, soportan dual channel desbalanceado (2+1 por ejemplo), mientras que las controladoras de AMD, no soportan esto.
This mode provides the most flexible performance characteristics. The bottommost DRAM memory (the memory that is lowest within the system memory map) is mapped to dual channel operation; the topmost DRAM memory (the memory that is nearest to the 8 GB address space limit), if any, is mapped to single channel operation. Flex mode results in multiple zones of dual and single channel operation across the whole of DRAM memory. To use flex mode, it is necessary to populate both channels.
Intel® Desktop Boards based on the following chipsets support Flex Mode:
NOTE: The use of flex mode requires DIMMs to be installed in both channels.
De la página de intel.