https://bugs.freedesktop.org/show_bug.cgi?id=93826
--- Comment #12 from Damien dherault@hotmail.com --- I've test to make a new mode : xrandr --newmode "2560x1440_144.00" 808.75 2560 2792 3072 3584 1440 1443 1448 1568 -hsync +vsync
But same issue.
Works with FGLRX @144Hz.