Geforce GTX 650 SC Multiple Display Problem

[iDiot]

As the title shows, I've got a Problem with my Graphics Card.
My System Runs OSX 10.9.5 smootly.
Recently I've found a 19" Monitor which I think runs a Resolution of 1400x900.
I want to hook It up to my Hacki, but if I want to use it it just doesn't scale correctly.
Do anyone has any kind of suggestions or solutions?

Sry for my bad english, I'm from germany

Thx to everyone.

 

[Bradjmeyer]

I had an issue when I first built my Hackintosh. My monitor would not scale correctly. I got a different monitor, and it worked fine. It was an old monitor. I currently use a tv.