Upgrading CPU and how to solve my RAM Problems

So a friend is upgrading their CPU and said they will sell me their old i7 3820 for a nice price. My problems start with the fact If I do buy this CPU I'll need to upgrade my Motherboard to the 2011 socket, not so bad, but as far as I know this MB/CPU is going to be quad channel memory. In my current system I have an older i7 930 that runs tri channel for which I recently bought new RAM now if I do go to upgrade what is the best approach to take with my RAM? I don't really want to buy a whole new set, while I was told that you can run dual channel as well on these MB/CPU that means losing out on one whole stick/4gb of RAM. Ideally If could find a single stick of Identical RAM I would have 4 but this is proving quite difficult. I have found a dual channel set, but again this means I'll have a left over stick of 4gb.



Does anybody know where I could find an single stick that would match, or anybody know if I could buy a similar stick and get it to work?





EDIT: Was talking to someone and they said most MB's now will be able to just run the 3 sticks as 3 single channel sticks.