I have the 514. I OC'd it using xrandr on Linux a few years back at 280Hz merely for testing. Mind you, the maximum supported vertical refresh rate of that monitor is 200Hz. Not sure on the resolution but it was way below 1024x768. The monitor at that refresh rate made a humming noise that scared me and I went back to 240Hz which did not produce any noise. Those monitors were beasts.

Trumpatized*