well i don´t know about others, but i´m not having problems with that.
Both my cards are running at full speed and nothing ever crashes.

Only problem I have is that i can´t oc my amd card while it´s not the main display adapter.
But i can simply plug in my monitor in the amd and oc.

I fixed this by applying my oc in the graphics bios.
Oc-ing nvidia cards is not affected by that.