When the screen goes black, does the PC crash, does it recover, or do you have to shut it down or reset it?
Take the overclock off of your card for testing. Does it still happen? Are there any error messages in the Windows Event Logs?
Is your 660Ti the original card you used in your system, or is it an upgrade from something else? If from something else, make sure you removed all the old drivers. Ccleaner is a free program that may help you complete that process if you aren't sure if you did.
What are your CPU and GPU temperatures when it black-screens? If your PSU is mounted in the bottom of your case, make sure the case isn't resting on carpet, which may be blocking the intake of cooling air for the PSU. I use an 8"-10" wide piece of thin plywood under my cases so the vents aren't blocked.
The pc doesn't crash and I don't need to recover it. I did take off the overclock settings and reset voltage. I increased voltage and played games like that for a while, maybe thats the problem 660ti is the original card, I got it brand new and havent had any problems with it. PSU brand I think is Antec and I'm not sure about model. It's the one with different lights. My 660ti temperature was normal, around 30-35C even when screen goes black. It looks like the blinking stopped for now, but I turned off Precision, and reinstalled drivers a couple of times, so we'll see