Screen freeze, mouse moves?

[cuddles]

When playing with my video card frequencies, whenever I put the core above 585, my screen will freeze, but the mouse will still be movable. I can't click on anything or do anything, but I can move the mouse. After a bit, if I try to hit CTRL-ALT-DEL, it goes black, but my monitor stays on (so it's still getting signal). What would be causing this?

[Ubermann]

I think you hit the limit where you need voltmods.