Running Multiple GPU on a single computer

[Jeffyu]

I have just set up a mining rig consisting of GTX 1080 Ti, 1070 and 1060. I got 2 question,

1) do I need to indicate which card is the primary card for gaming? and the rest as the secondary cards. how do I do it? Or will the CPU automatically select the fastest card as the primary?

2) can MSI afterburner control the clock speed of multiple GPU? if they can't what are the alternative?

 

[BurgerandChips66]

For gaming make sure the 1080Ti is installed in the primary PCIe slot (usually the slot nearest the CPU). Then plug your monitor into that card.
When gaming, the other cards will now not be used (unless you happen to be playing a DX12 game with m-GPU support).