As title....especially when notepad.exe (white screen) is open....the screen has flickering lighter/darker

Hello. two questions, both quite important i had a packard bell i3 2370, very quiet machine. my fujitsu a531 i5-2450 (5 days old bought new) fan has a fairly noisy rasp spinning up every few seconds. is this as per the design...would an a531 i3-2350 be quieter ? (or a replacement i5?) also, VERY imp...