|Judging by your post it certainly sounds, as you say, that those two sticks of RAM are the cause. You haven't posted any PC or mobo specs so I can't even check whether or not 4GB sticks are compatible, if it's a very old PC they may not be.|
May be faulty RAM so buy 2 sticks from somewhere else.
Make sure the RAM exactly matches the specs of what is compatible with your system, especially the speed of the sticks, and make sure it's unbuffered & non-ECC.
message edited by phil22