At least I think it's the monitor. After a bit of use, screen blanks. Everything running is still running, and the light on the power button doesn't change to the stand-by mode. The only way I have found to get it back is to turn it off, then back on.
I'm pretty sure it's the monitor and not the graphics card because it does it when you are at the log in screen, in a browser, running Vscan... Just randomly and nothing GPU intensive.
Ran the GPU burn in test... Monitor blanked out twice in the beginning, then stayed on for about a half hour as I was messing with other things before dinner/walk. I thought to myself, "maybe it just needed the cobwebs kicked out of it." During the test, temps got to 78 C and stayed there, and the fan only sped up to 55% (normally at 40%). So I turned off the monitor when we went on a walk. Got back, got the kids in bed, etc etc. Popped on and surfed, and played a few games and after about an hour it went blank Turned it off, then back on and it went blank again about 20 sec later. I turned the monitor off, then waited about a minute and after I powered it back on, it stayed on for about 3-5 mins.
I reproduced the same thing earlier today as well. I didnt stop anything that was running/on-screen when I turned the monitor off, so theoretically the image should still be beaming from the card, no matter if anything is displaying it or not.
Semi conclusion: monitor is overheating or something weird going on with cables (tight and look good no outward scarring) or internal comps. I need to find a spare around to test though.