Screen flickering may appear from two causes: one, the monitor is faulty and needs to be replaced and second, the video card is not working properly. The most probably is that the video card is stressed using a higher resolution and it overheats which in this case the fan is spinning at a low speed. Increase the fan speed with a tweaking application but be aware to modify only the speed to the main fan only. Also, another possible problem is with your PSU unit. If you are playing a game which requires many resources and the devices consume more than the PSU’s power then you need to replace it. Contrary, it has been reported that the cause to these flickering problems are the drivers itself. Downgrade the drivers and analyze the problem again. Perform the same step if there are newer drivers available for the graphic card.