Yea, I tried this but I also read my gpu is locked to 80 hz so I just don't know. I'll try again. I also read that these monitors come able to be over clocked by just going into the settings, which made me curious if my gpu is limiting it.
Are you going to game on this monitor? I don't know about the 5000 series being locked at 80Hz or if you can/how to break the driver, but a 5850 won't even be able to push pixels to a 1440p monitor at 60Hz, at least not in AAA stuff.
I have that monitor, but I am running on a GTX 770 4GB. The monitor does work well and I have overclocked it to 120Hz with no issues whatsoever (using nvidia control panel). I think the safest bet will be the 290x as that 5850 will not have the horsepower to render games at that resolution.