[arch-general] Problems with flickering monitor

Hi, i have a problem with my monitor, since when upgraded with pacman -Syu then when reboot the PC i could not start Arch, but if in fallback. Since my monitor flashes almost second. Then i don't know because walked in normal mode but continues with flashes. My archive /etc/X11/xorg.conf is empty and i have not installed drivers for my plate NVidia. There is a way for configurated the monitor. -- Dario PD: sorry my english, your understanding