15.04: I can't change the resolution of my second screen (Nvidia)

I have installed the last proprietary Nvidia driver installed (346.59) on a GTX 750 card. After the upgrade to 15.04 (Kubuntu) I can't change the resolution of my second screen up to 800x600. 340 driver is the same.

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What is the problem ?

Edit: This is the same problem here, I had to find the EEID of my screen.


Solution 1:

The 340.76 version from edgers ppa works:

sudo apt-add-repository ppa:xorg-edgers/ppa
sudo apt-get update
sudo apt-get install nvidia-340