I am having the exact same issues on the same computer. If you find out whats causing it I'd love to hear what works for you.
I first updated the driver to 285 about a month ago because of some lag issues on a previously very smooth running game.
That didn't help but now this issue with the screen blacking out and there has even been some messed up pixel-looking things along the top and bottom of my screen. I would take a screenshot but they are not captured in the screenshot. I've blown out the unit and I've been using a Thermaltake usb fan.
Maybe its just time to get a new card?
Edit: Also, I use the MSI Afterburner for keeping track of my temperature and when I'm not running a game the GPU temperature is 50-53 degrees Celsius, and running a game can be anywhere from 70-80 degrees Celsius.