Ryzen is loves memory speed so much. Your likey to get more performance from a memory OC then actually OC'ing the actual cpu!
So does this imply to quad channel over dual channel?
The number of memory channels is built into the memory controller, which on modern desktop CPU's is built into the CPU itself. Ryzen is dual channel, period. (As is Intel Coffee Lake desktop CPU's.)
You can run 4 memory sticks but that doesn't make it quad channel. It just means that you are putting two sticks on one channel, which puts a more difficult load on the memory controller and is likely to slow things down. The ideal in terms of speed potential for Ryzen and Intel desktop CPU's is two sticks, one for each channel.
To add to the other comments here, if you look at the QVL lists for most motherboards, they usually only certify the XMP clocks when 2 sticks are used. It's well documented that Ryzen doesn't really like 4 sticks.
Just to run this into the ground, if you want 4 channels on your AMD CPU you need to go with a threadripper.
I think EPYC will go 8 channel.
but it's not quad channel thou...
Besides it runs best with 2 sticks