How to add a 3rd monitor?

[ejlif]

I have two monitors in my main room. I'm think of just running a cord with another monitor into my second room and just using a wireless keyboard and mouse. How would I hook this up? USB cord. I have now an iMac and and extra thunderbolt display. The thunderbolt display has an open USB connection and a thunderbolt as well as firewire 800 and also ethernet. Just wondering what the best route to go it here? The room is just right next to my main control room so I just need to get about a 20' cord and run it through the wall.

[mekanism1200]

I have used a Chromecast with screen mirroring for a third monitor and it works OK, a tiny bit of lag but it's usable.

[beats me]

Sounds to me like you might just need a thunderbolt cable.

[ejlif]

I was hoping to just have an extra monitor permanently set up in the other room so I wouldn't have to move anything when I want to use it. I chatted with the mac store people and they said 2 displays only. Can that be right? I just need to mirror the arrangement window on the other monitor. I don't really need anything fancy but if I had to I would buy another thunderbolt display.

[beats me]

You could also get a cheap iPad (if you don’t already have one) and use a mirroring app or controller app.

Somebody posted this exact same scenario about a month ago and got annoyed we would even suggest such an option.

[Stromkraft]

I was hoping to just have an extra monitor permanently set up in the other room so I wouldn't have to move anything when I want to use it. I chatted with the mac store people and they said 2 displays only. Can that be right?

What on the iMac would drive the third display? That's commonly the limiting factor. If the graphics card can drive 3 displays, fine. If not, you need another solution that can make up for this.

Some people have looked into this issue though:
How To Run 3 Displays on an iMac.