maximum external screen for dell XPS15z (Geforce525M)

[addeconin]

I wondered what the maximum resolution is that I can use on a dell XPS15z with Geforce 525M (2GB) when I want to use the laptop screen and external screen at the same time.
I contacted dell, but they say , max resolution external screen = resolution laptop screen which seems odd to me.
I failed to find any spec on dell or nvidia site that specifies this.

 

[Lonyo]

What outputs does the laptop have?
It should be capable of running 1920x1200 for sure, since any combination of GPU and display output can manage that, but above that it might struggle if the laptop doesn't have the right sort of output.

 

[RavenSEAL]

It should be capable of whatever the max resolution of that display is. If my crappy HP laptop can do it, so should yours.

 

[zuffy]

Mine is the XPS 15 but same video card. I can output to my Apple 27" @ 2560 x 1440 with no problem.