Nobody can tell you anything without proper system info or other technical details like exact comp settings, render settings and what have you.
AMD 4300 (overclocked to 4.4 ghz)
GT 610 1gb (overclocked by 100 mhz)
Those are the main parts but They have never caused problems.
Figured it out:
For some reason, a bit of film has to layover another to work. No clue why but solved. (i just did 1 frame of overlay, dont know what caused it still.)