adding a second graphics card

Solution
Yes but you will need an SLI HB Bridge which pairs them together and make sure your Power Supply is enough to handle 2x GTX 1080. Just also making sure you have a case that has the necessary space for the 2x radiators on your Hybrid 1080. Hope this helps :)

*Edit* Most modern mid-high end Motherboards come with an SLI bridge if they support it (my 3 boards over the years have all come with one) or you need to buy one i believe they are under $50 USD.

CRO5513Y

Expert
Ambassador
Yes but you will need an SLI HB Bridge which pairs them together and make sure your Power Supply is enough to handle 2x GTX 1080. Just also making sure you have a case that has the necessary space for the 2x radiators on your Hybrid 1080. Hope this helps :)

*Edit* Most modern mid-high end Motherboards come with an SLI bridge if they support it (my 3 boards over the years have all come with one) or you need to buy one i believe they are under $50 USD.
 
Solution
It totally depends on motherboard, if it supports SLI.
If it doesn't, then no - it wont work.
And of course PSU must be sufficient to provide necessary power to such setup.