Yep - but then there are two things:Did you know that both Unity and Real Engine have both become very multi-core friendly?
When will we see something of it in simracing titles? Currently there's no sim really being able to max out even 4 cores.
And the second thing: if a game would be able to max out 6 cores completely you would have such high fps numbers that the gpu wouldn't be able to keep up anyway as the new VR headsets and ultra wide 1440p and 4k monitors are constantly hitting the market too.
You mobo etc choices look well researched. I sadly can't comment on this but I doubt you'll end up buying something bad anyway with your current knowledge