Clearly if you can return it, do it....
Why does everyone claim that you get single channel. Flex mode allows you to get most of the benefits of dual/tri channel with odd numbers of sticks. This has been a standard feature from Intel for quite a while.
Here ya go
I7 with 4 sticks(out of the 6 slots the board has) in triple channel mode. The other 2 sticks are in an AMD system that had bad memory.
I would test in my I5 system, but it is an itx system and as such only has 2 memory slots.
I honestly can recommend the I5(after all most if the I5's have much more aggressive turbo) for most applications.