Was the RAM causing distorted graphics on my pc?

i was on my pc playing a game and then as soon as i minimized to check facebook a few columns of white dots appeared over the screen, i restarted the computer and at the post screen these white column dots appeared again, i was still able to log into the desktop screen but when i kicked on the exe to launch the game i was kicked off after 5 seconds of the intro, i then took out one of the sticks of ram and everything was fine again :) my pc is overclocked and the stick of ram i took out was the older one. what do you think happened? why did they occurred?