Can't select native 2560x1080 res on Linux Mint 17.2 (Nvidia ION 340.67 driver)

Clueless here. I’m running Linux Mint 17.2 on a Asrock ION 330 with a Nvidia ION gpu. The screen is a LG Ultrawide (25UM65) with a native 2560x1080 res. The ION supports up to 2560x1440 but the native res isn’t selectable on nvidia-settings.

On the ‘X Server Display Configuration’ > ‘Advanced’ I can input 2560x1080 manually in the ‘ViewPortIn’ and ‘Panning’ field but it looks very very fuzzy. Non-workable. I’ve tried all possible solutions through Google search but non works.

On other OSes it looks great (on the same hardware) so does anyone have an idea if this is a driver bug or some sort?

Same problem here.

I have 25UM65 and GeForce 9800GT. In Windows (on the same PC) I use 2560×1080 without problems, the resolution is automatically adjusted.

But in Linux I can’t set above 1920×1020. The proprietary driver is updated. I’ve tested on Mint and Manjaroo.

What should I blame? The driver?