What cause this problem, RAM or any other hardware?

I will make two guesses. 1. there is a RAM mismatch. RAM modules should be from same manufacturer and same speed. Remove the additional RAM module you added and try to operate the computer.2. Your power supply is not sufficient. Calculate the power from this web site and add 20% to the value obtained. a href="http://extreme.outervision.com/psucalculatorlite.jsp" rel="nofollow"http://extreme.outervision.com/psucalcul…/a