One related question. Is brand a restriction i.e. does for eg. all should be Sapphires or Sapphires can be mixed with XFXs within the same 400 series?
Regards,
Riz
They can be mixed fine. My rig of 1060s has two Asus cards, a PNY card with a blower-style cooler, and 3 other PNY cards. I also have a rig of HD 7000 series cards with Asus, MSI, XFX, and PowerColor cards.
Sometimes different models of a card can come with different clock settings, so you may want to watch for that (especially if you use MSI Afterburner's "sync settings for similar gpus" setting, or something similar), since some cards that come factory OC'd could have significantly better overclocking potential than your other cards. (Although overclocking capabilities will vary on your cards, even within the same brand and model.)