Actually, you do have enough info.... Several reliable sources on this forum have said that the OS and the beta driver work fine together, so there is no inherent conflict. If there was, it wouldn't work on my 8-core and it does.
So, that's not it. I was just pointing out that speculation is never a good approach to problem solving. There is something on the two machines with trouble that isn't on the MB, but it's not Mavericks.... Something else is conflicting with your driver.
Besides, if you are running the beta driver, then you should be reporting these problems to RedBus, not trying to fix them here... Not all of us are running that driver or have upgraded to 10.9.