Can one memory channel inside a cpu package be broken?

I had 2 sticks of 16GB so 32GB total working in single channel mode in my previous motherboard. I wasn't aware it was running in single channel mode, the sticks sat in slot B1 and B2. When I tried to upgrade it to 64GB with two other sticks of the same model, I noticed that whenever there is a stick present in slot A1 or A2, the computer didn't want to POST.
I got a replacement motherboard because of this and unfortunately I ran into the same exact issue. I put my i7-6700K into it and it won't boot with ram in channel A. Can this be a partially broken CPU where somehow memory channel A is fried inside the CPU but channel B still works fine? I got the CPU second hand. I tested all my memory sticks and they all work fine on their own in channel B on either motherboard.