Can't get max resolution on external display?

[Ritte]

Hi, I have a dell u2713hm and at the moment my mbp mid-2010 15" can't display more than 1080p. I'm using mini-dp to dp and I used to get maximum resolution before. But this morning my computer froze in login screen and I restarted it. After that I only have 1080p.
On my macbook air 2012 I can get max resolution by using the same cable.

Is my gpu on my mbp dead?

 

[Ritte]

When looking in the system report it shows that the gpu is running the external display. Odd, it can't be dead then.

Edit: Booted up in my backup drive and I could choose max resolution from there. Booted back up to main drive and had to switch between several resolution before I could choose max resolution. But it works now.

Wierd.