I recently bought the LG 29UC88 widescreen monitor which has a resolution of 2560x1080 and operates at 60hz.
I also bought a card with the Radeon HD 7450 chipset to drive it. The attractive feature of this card is that the free radeon driver supposedly supports it quite well (see the "N. Islands column" of https://www.x.org/wiki/RadeonFeature/).
Unfortunately on Ubuntu 16.10 this card/monitor pair does not work out of the box (with an HDMI connection). I've managed to get the proper resolution using the card at 30hz instead of 60hz using hints from another post (https://askubuntu.com/a/818153/14747).
xrandr --newmode "2560x1080_30.00" 106.75 2560 2640 2896 3232 1080 1083 1093 1102 -hsync +vsync xrandr --addmode HDMI-0 "2560x1080_30.00" xrandr --output HDMI-0 --mode "2560x1080_30.00"
This is rather disappointing since the result is choppy. Does someone know how to get this this thing working at the full 60hz?