Do a clean install of different drivers,for example for the first time,use the latest VGA driver,if it didn't help,try an older one.Here is how to perform a clean install
1_Download driver sweeper(from guru3d.com)
2_Go to control panel and uninstall the current driver from there
3_Reboot and go to safemode and open driver sweeper and click on Nvidia,then choose clean
4_Boot normally and Install the new driver
When i try to download the sweeper it says "unable to execute file, this process requires elevation."