Lately, my screen has been randomly shutting off and going into power saving mode. I've updated the drivers, ran memtest, cleaned up and defragmented my drives, and my temperatures are way cool, so I'm not sure what's going on with it. Any ideas/suggestions would be much appreciated.
Have you recently made any changes to your system?
For example, have you installed any new hardware or changed any power connections inside the case? Have you changed any Power Options in the Control Panel?
Think of any changes you may have done to your system prior to the first time you experienced the problem.
Regardless, check your Power Settings. There is an option there to turn off the monitor if the PC is idle for longer than 1 minute. Is this your case, perhaps?