Seeing double after having monitor turned off

So my 660 has never given me any problems until about 2 days ago. Since then, twice it has had a stange issue. It seems to only happen if i leave the pc running (doing virus scans or downloading games) and i turn off the monitor for a few hours. Twice when i have turned the monitor back on it has displayed as though the screen picture is being displayed twice, but with one of the images slightly offset with the other. When this happens i cannot get it to go away unless i restart the pc. Once i do that, everything is fine. Turning the monitor off and then on again doesnt fix it and the monitors built in menus appear fine while the issue is happening, so i dont think it is tge monitor that is having the issue. I did move my system over to a new case about a month ago, but if that affected something i would think my issue would happen more often. Any clue what it could be?
 
I had a similar issue with my old monitor, it was slightly ghosted (only noticeable if I looked for it), I had it for months before I decided to try and fix it, I switched the cable and it was fine. Although it going away when you reboot could be something else.
 
Yeah, im thinking it isnt the monitor because it only happens every once in a while, plus the restart fixing it. Its not so much a ghosting thing as it is a duplicate image that is offset a little. I will try and get a screen capture (if it will capture it).