Clone then downscale?

[Draminicus]

 Long story short, I'm looking to buy a new monitor, instead of getting 3 to do the panoramic view for games, I was thinking of just getting an ultra wide and calling it a day. My issue is I stream content to a second PC using an Avermedia Gc550 which only captures at 1080p.
MY question is, using a GTX 1070 can I clone the signal then downscale the one going to the  Capture Card, and if so how bad is this going to affect my performance?

[Electronics Wizardy]

The problem with ultra wides and streaming is almost all viewer will have black bars when watching. Id suggest going with a 16:9 display or running a 16:9 resolution when streaming so viewers down have black bars.