Dual Monitor Query From a Noob

Hey there, first of all I'd like to apologise if I've put this in the wrong section as I'm not quite sure what it would fall under.

Basically, I'm planning on building my first gaming pc once I've saved up enough money, and have decided on a 27" 1080p AOC screen for my monitor. But then I had the idea to also add a small, possibly 18" 720p screen as a secondary monitor so that I'll be able to check things like Skype or any recording/streaming software I may be using without exiting full screen on my main monitor. 

My query is, will running a small secondary screen affect my framerate in a noticeable way? And if so would it be in my interests to also add an extra (budget) GPU to my system to drive the second monitor? I'm not sure, nor am I able to devise through research whether it's possible to run separate GPUs not in Crossfire or SLI, and I understand that Crossfiring a fairly decent GPU with a crappy one would sap the capabilities of the better GPU.

Any insight you could give would be greatly appreciated; and in case it matters, I plan on using an MSI R9 270X Hawk edition card.

Thanks in advance :)

there will be no performance loss by running multiple monitors

I think you'll do just fine with two monitors and the MSI R9 270x with out seeing any real performance drop in your games.

In fact I recommend two monitors, after going to two monitors one just feels crowded.

Okay, thanks for the help.

That's what I was hoping for, thank you for clarifying that for me.