Glad you got it all figured out. 16x16 and 8x8 make no difference in most configurations as of now. In crossfire/sli, they are hamstrung in the same way. Most people are going single GPU nowadays due to the lackluster multigpu support.
There is nothing to figure out, just a fact. It does make difference sorry and 4k gaming is not going away and with the faster video card it is going to make a major difference.